Hi, I have a query about the functionality of Evolution as a mail package.
Does Evolution support the tagging of outgoing mails as "organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately? Does Evolution, when using IMAP, provide the functionality to leave the mails on the server or mirror them locally if desired? Does Evolution, when setting up the mail interface, provide the functionality to auto configure the mail server definitions or do you have to set them up manually? I'm trying to test some mail sensitivity issues at work and Thunderbird doesn't support that functionality.
regards, Steve
On 3/19/25 3:11 PM, Stephen Morris wrote:
I have a query about the functionality of Evolution as a mail package.
Does Evolution support the tagging of outgoing mails as "organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
Do you have an example of an email client that supports automatically tagging outgoing email? Thunderbird can certainly tag incoming emails according to headers.
Does Evolution, when setting up the mail interface, provide the functionality to auto configure the mail server definitions or do you have to set them up manually?
Does your domain have that configured?
On Thu, 2025-03-20 at 09:11 +1100, Stephen Morris wrote:
Does Evolution support the tagging of outgoing mails as"organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
I don't actually know what you mean by organisation-sensitive or sensitivity level, I can only guess.
Filters can be set that will read headers in incoming mail that can set labels, assign colours, assign/adjust scores.
But I found out, long ago, that when it comes to labelling messages it just sets something *like* label1, label2, label3, and you have to assign meanings to those labels on the client (work, home, later). And they only mean something to it on *that* client. If a label1 message is read on another client that set up their labels in another order, it gets whatever they set up on their label1. About the only well supported flag I know of in email is the "important" or prioritise flag.
With various email clients, these labels or flags are not put into the message body (nowhere that I can see), they're in the metadata that the client keeps in its own index or added to the filename the email is stored as when using maildir (likewise with some mail servers).
In the past I'd received emails from a government source which came with a "classification" level somewhere, but it's not something you see in everyday mail, so whether there's a standard for it, or they just bung text in the subject line, I do not know.
Looking through my archives, I see they shoved [SEC=UNCLASSIFIED] onto the end of the subject line, and had these headers:
x-protective-marking: VER=2012.3, NS=gov.au, SEC=UNCLASSIFIED, ORIGIN=their-email-address-was-here x-original-protective-marking: VER=2012.3, NS=gov.au, SEC=UNCLASSIFIED, ORIGIN=my-email-address-was-here x-classifier: janusSEAL for Outlook 2.6.2
The x- prefix indicates something non-standard, and I suspect only means something to their internal mail system. Evolution can be set to show headers of your choice in the mail reading window pain, but you're not going to see an interpreted result, just all that raw text after the header.
I think they'd have at least three ways of doing that: Custom mail software, custom plug-in for the mail software, processing by the mail server before sending.
Email signatures can be used to add boilerplate notices, but for organisations that *require* such things and don't want it it left up to an email author to use their email program properly, it's often done by their mailserver as they process outgoing mail.
I suppose you could set up a few different signatures on the client, that the mail server would react to and set other headers appropriately. That's work with almost any email client that lets you pick a specific signature when you write a message.
There are various add-ons to emails that are custom and rely on specific software, or so rare that hardly anything implements them. (again, relying on using specific software). And it's relying that any replies to such special messages keep special headers in their replies, which they probably won't.
Does Evolution, when using IMAP, provide the functionality to leavethe mails on the server or mirror them locally if desired?
Yes, Evolution does what IMAP is intended to do and leave emails on the server. And it can do local caching.
Does Evolution, when setting up the mail interface, provide thefunctionality to auto configure the mail server definitions or do you have to set them up manually?
There is a feature where it pulls configuration data from a well-known address on a server (*). Some (other) mail clients seem to do this not by querying the domain of the mail server you're wanting to use, but some global database which obviously only works for services listed with that database.
If your mail server was example.com and you started to set up an account on Evolution for johndoe@example.com it'd try: http://autoconfig.example.com/mail/config-v1.1.xml to fill in all the other technical details for the user. Which, according to the specs, could simply be general mail server stuff, or can have user-specific details.
At least that address works when I set up my mail system, I don't know if there's other variations on the well-known address.
On Wed, Mar 19, 2025 at 10:21 PM Tim via users users@lists.fedoraproject.org wrote:
On Thu, 2025-03-20 at 09:11 +1100, Stephen Morris wrote:
Does Evolution support the tagging of outgoing mails as"organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
I don't actually know what you mean by organisation-sensitive or sensitivity level, I can only guess.
https://www.google.com/search?q=data+classification+and+sensitivity+levels.
(I would have sent it privately, but emails to your email address bounced).
Filters can be set that will read headers in incoming mail that can set labels, assign colours, assign/adjust scores.
But I found out, long ago, that when it comes to labelling messages it just sets something *like* label1, label2, label3, and you have to assign meanings to those labels on the client (work, home, later). And they only mean something to it on *that* client. If a label1 message is read on another client that set up their labels in another order, it gets whatever they set up on their label1. About the only well supported flag I know of in email is the "important" or prioritise flag.
With various email clients, these labels or flags are not put into the message body (nowhere that I can see), they're in the metadata that the client keeps in its own index or added to the filename the email is stored as when using maildir (likewise with some mail servers).
In the past I'd received emails from a government source which came with a "classification" level somewhere, but it's not something you see in everyday mail, so whether there's a standard for it, or they just bung text in the subject line, I do not know.
Looking through my archives, I see they shoved [SEC=UNCLASSIFIED] onto the end of the subject line, and had these headers:
x-protective-marking: VER=2012.3, NS=gov.au, SEC=UNCLASSIFIED, ORIGIN=their-email-address-was-here x-original-protective-marking: VER=2012.3, NS=gov.au, SEC=UNCLASSIFIED, ORIGIN=my-email-address-was-here x-classifier: janusSEAL for Outlook 2.6.2
The x- prefix indicates something non-standard, and I suspect only means something to their internal mail system. Evolution can be set to show headers of your choice in the mail reading window pain, but you're not going to see an interpreted result, just all that raw text after the header.
I think they'd have at least three ways of doing that: Custom mail software, custom plug-in for the mail software, processing by the mail server before sending.
Email signatures can be used to add boilerplate notices, but for organisations that *require* such things and don't want it it left up to an email author to use their email program properly, it's often done by their mailserver as they process outgoing mail.
I suppose you could set up a few different signatures on the client, that the mail server would react to and set other headers appropriately. That's work with almost any email client that lets you pick a specific signature when you write a message.
There are various add-ons to emails that are custom and rely on specific software, or so rare that hardly anything implements them. (again, relying on using specific software). And it's relying that any replies to such special messages keep special headers in their replies, which they probably won't.
Does Evolution, when using IMAP, provide the functionality to leavethe mails on the server or mirror them locally if desired?
Yes, Evolution does what IMAP is intended to do and leave emails on the server. And it can do local caching.
Does Evolution, when setting up the mail interface, provide thefunctionality to auto configure the mail server definitions or do you have to set them up manually?
There is a feature where it pulls configuration data from a well-known address on a server (*). Some (other) mail clients seem to do this not by querying the domain of the mail server you're wanting to use, but some global database which obviously only works for services listed with that database.
If your mail server was example.com and you started to set up an account on Evolution for johndoe@example.com it'd try: http://autoconfig.example.com/mail/config-v1.1.xml to fill in all the other technical details for the user. Which, according to the specs, could simply be general mail server stuff, or can have user-specific details.
At least that address works when I set up my mail system, I don't know if there's other variations on the well-known address.
Jeff
Tim:
I don't actually know what you mean by organisation-sensitive or sensitivity level, I can only guess.
Jeffrey Walton:
https://www.google.com/search?q=data+classification+and+sensitivity+levels.
Yes, I mentioned classifications further below in my email. The organisation-sensitive one was a new one on me (R&D only? LegalDept only?). Though, without the original poster responding, I don't know if it's just about labelling the messages or is meant to enforce controls.
I suspect it's merely a label and application-specific. The moment you email someone without the requisite software it's going to get ignored.
Like typing "private and confidential" at the top of a letter, it does little more than advise the person reading it.
They're likely to find that if their organisation requires access controls, they probably require specific approved software. One that's been vetted and tested and they don't want to pay to test anything else. Amusingly, it'll probably be some Microsoft app that's approved, despite it having numerous other major security flaws that should get it vetoed.
https://www.rfc-editor.org/rfc/rfc2156#section-5.3.4 https://www.rfc-editor.org/rfc/rfc4021#section-2.1.55
Seem to indicate it's only going to be a label in the header. Someone in a committee is probably going to get their knickers in a twist insisting something actually useless must be mandated.
Going back to serious mode: I see nothing in Evolution that offers the feature, except for appointments in the calendar. You'd probably have to have a custom plug-in created. That, or some kind of automatic processing done by the mail server looking for keywords to trigger it (such as choosing different boilerplate signatures, to give a simple way to choose an option in the message editor).
I think this is another of those things that is glossed over in email, like how damn difficult it is to do secure mail (it's still definitely computer nerd territory to encrypt emails).
(I would have sent it privately, but emails to your email address bounced).
The list replaces my from address with its own, so that won't work. I know why it does that, in general, just not specifically why it does that to mine (they're posted directly through a major server that requires me to login). Not that I care, I'm happy with it doing that.
If people read my boilerplate they'd see they can't reply privately, in any way.
On Thu, 2025-03-20 at 09:11 +1100, Stephen Morris wrote:
Hi, I have a query about the functionality of Evolution as a mail package.
You might want to ask on the Evolution mailing list. See https://lists.osuosl.org/mailman/listinfo/evolution-users
There's also a Gnome Discourse forum at http://discourse.gnome.org. Note that the two things are not cross-linked and are run independently (full disclosure: I was instrumental in setting up the current mailing list and am one of its moderators, under a different email address).
Does Evolution support the tagging of outgoing mails as "organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
Not that I know of. I don;t recall ever seeing someone request this, but ask away. The main Evolution developer is very responsive.
Does Evolution, when using IMAP, provide the functionality to leave the mails on the server or mirror them locally if desired?
Yes.
Does Evolution, when setting up the mail interface, provide the functionality to auto configure the mail server definitions or do you have to set them up manually?
Depends on the server, but mostly it's automatic.
poc
*From:* Samuel Sieb samuel@sieb.net
*Sent:* Thursday, 20 March 2025 at 09:49 UTC+11
*To:* users@lists.fedoraproject.org
*Subject:* RE: Evolution Functionality
On 3/19/25 3:11 PM, Stephen Morris wrote:
I have a query about the functionality of Evolution as a mail package.
Does Evolution support the tagging of outgoing mails as "organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
Do you have an example of an email client that supports automatically tagging outgoing email? Thunderbird can certainly tag incoming emails according to headers.
Thunderbird does not have any support for mail headers tagging sensitivity levels, nor does it provide the ability to actually tag a mail as sensitive. I've seen an article on the net that was saying a request for that functionality has been outstanding for, I think it said, 12 years.
Does Evolution, when setting up the mail interface, provide the functionality to auto configure the mail server definitions or do you have to set them up manually?
Does your domain have that configured?
When I was using the email address provided by my isp, and using a gmail address, both environments provide Thunderbird with the ability to auto define the mail servers irrespective of whether you want to use IMAP or POP3.
regards, Steve
*From:* Tim via users users@lists.fedoraproject.org
*Sent:* Thursday, 20 March 2025 at 15:08 UTC+11
*To:* noloader@gmail.com, Community support for Fedora users users@lists.fedoraproject.org
*Cc:* Tim ignored_mailbox@yahoo.com.au
*Subject:* RE: Evolution Functionality
Tim:
I don't actually know what you mean by organisation-sensitive or sensitivity level, I can only guess.
Jeffrey Walton:
https://www.google.com/search?q=data+classification+and+sensitivity+levels.
Yes, I mentioned classifications further below in my email. The organisation-sensitive one was a new one on me (R&D only? LegalDept only?). Though, without the original poster responding, I don't know if it's just about labelling the messages or is meant to enforce controls.
When sensitivity levels are set on a mail, the mail client adds headers into the header list to specify the sensitivity level specified (Private, confidential, organisation-confidential). The setting of organisation-confidential is the same as confidential but meets the requirements of RFC 256 (I think it was that, I need to look up the documentation again for the environment I develop in at work to see exactly what RFC it is for).
I suspect it's merely a label and application-specific. The moment you email someone without the requisite software it's going to get ignored.
Organisations, if they so desire, can put processes in place to handle mails with headers specifying sensitivity differently to mails that don't have the headers. In fact, I'm trying to get a defect resolved at the moment where somewhere between the code I wrote to send the mail and the mail arriving in Outlook 365, the sensitivity level in the headers has been changed.
regards, Steve
Like typing "private and confidential" at the top of a letter, it does little more than advise the person reading it.
They're likely to find that if their organisation requires access controls, they probably require specific approved software. One that's been vetted and tested and they don't want to pay to test anything else. Amusingly, it'll probably be some Microsoft app that's approved, despite it having numerous other major security flaws that should get it vetoed.
https://www.rfc-editor.org/rfc/rfc2156#section-5.3.4 https://www.rfc-editor.org/rfc/rfc4021#section-2.1.55
Seem to indicate it's only going to be a label in the header. Someone in a committee is probably going to get their knickers in a twist insisting something actually useless must be mandated.
Going back to serious mode: I see nothing in Evolution that offers the feature, except for appointments in the calendar. You'd probably have to have a custom plug-in created. That, or some kind of automatic processing done by the mail server looking for keywords to trigger it (such as choosing different boilerplate signatures, to give a simple way to choose an option in the message editor).
I think this is another of those things that is glossed over in email, like how damn difficult it is to do secure mail (it's still definitely computer nerd territory to encrypt emails).
(I would have sent it privately, but emails to your email address bounced).
The list replaces my from address with its own, so that won't work. I know why it does that, in general, just not specifically why it does that to mine (they're posted directly through a major server that requires me to login). Not that I care, I'm happy with it doing that.
If people read my boilerplate they'd see they can't reply privately, in any way.
On 3/20/25 2:53 PM, Stephen Morris wrote:
*From:* Samuel Sieb samuel@sieb.net
*Sent:* Thursday, 20 March 2025 at 09:49 UTC+11
*To:* users@lists.fedoraproject.org
*Subject:* RE: Evolution Functionality
On 3/19/25 3:11 PM, Stephen Morris wrote:
I have a query about the functionality of Evolution as a mail package.
Does Evolution support the tagging of outgoing mails as "organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
Do you have an example of an email client that supports automatically tagging outgoing email? Thunderbird can certainly tag incoming emails according to headers.
Thunderbird does not have any support for mail headers tagging sensitivity levels, nor does it provide the ability to actually tag a mail as sensitive. I've seen an article on the net that was saying a request for that functionality has been outstanding for, I think it said, 12 years.
What does that even mean? What effect would "tagging a sensitivity level" have? You didn't answer my first question. Do you have an example of an email client that does what you want?
Does Evolution, when setting up the mail interface, provide the functionality to auto configure the mail server definitions or do you have to set them up manually?
Does your domain have that configured?
When I was using the email address provided by my isp, and using a gmail address, both environments provide Thunderbird with the ability to auto define the mail servers irrespective of whether you want to use IMAP or POP3.
Ok, but you're referring to some other environment. gmail and your ISP probably have the automatic config information available. But does your environment?
On Thu, Mar 20, 2025 at 6:22 PM Samuel Sieb samuel@sieb.net wrote:
On 3/20/25 2:53 PM, Stephen Morris wrote:
*From:* Samuel Sieb samuel@sieb.net
*Sent:* Thursday, 20 March 2025 at 09:49 UTC+11
*To:* users@lists.fedoraproject.org
*Subject:* RE: Evolution Functionality
On 3/19/25 3:11 PM, Stephen Morris wrote:
I have a query about the functionality of Evolution as a mailpackage.
Does Evolution support the tagging of outgoing mails as"organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
Do you have an example of an email client that supports automatically tagging outgoing email? Thunderbird can certainly tag incoming emails according to headers.
Thunderbird does not have any support for mail headers tagging sensitivity levels, nor does it provide the ability to actually tag a mail as sensitive. I've seen an article on the net that was saying a request for that functionality has been outstanding for, I think it said, 12 years.
What does that even mean? What effect would "tagging a sensitivity level" have? You didn't answer my first question. Do you have an example of an email client that does what you want?
I'm not speaking for Stephen... But Microsoft supports sensitivity levels in Office 365. See https://support.microsoft.com/en-us/office/apply-sensitivity-labels-to-your-files-2f96e7cd-d5a4-403b-8bd7-4cc636bae0f9.
For general email, I believe you can use the Sensitivity: email header from RFC 1327. Or maybe use an X-header.
The BNF for RFC 1327 Sensitivity: is kind of lame:
sensitivity = "Personal" / "Private" / "Company-Confidential"
So I would expect to see modern mail user agents use the X-headers to express finer grain classification.
Does Evolution, when setting up the mail interface, provide thefunctionality to auto configure the mail server definitions or do you have to set them up manually?
Does your domain have that configured?
When I was using the email address provided by my isp, and using a gmail address, both environments provide Thunderbird with the ability to auto define the mail servers irrespective of whether you want to use IMAP or POP3.
Ok, but you're referring to some other environment. gmail and your ISP probably have the automatic config information available. But does your environment?
Jeff
On Fri, 2025-03-21 at 09:08 +1100, Stephen Morris wrote:
When sensitivity levels are set on a mail, the mail client adds headers into the header list to specify the sensitivity level specified (Private, confidential, organisation-confidential). The setting of organisation-confidential is the same as confidential but meets the requirements of RFC 256 (I think it was that, I need to look up the documentation again for the environment I develop in at work to see exactly what RFC it is for).
I suspect it's merely a label and application-specific. The moment you email someone without the requisite software it's going to get ignored.
Organisations, if they so desire, can put processes in place to handle mails with headers specifying sensitivity differently to mails that don't have the headers. In fact, I'm trying to get a defect resolved at the moment where somewhere between the code I wrote to send the mail and the mail arriving in Outlook 365, the sensitivity level in the headers has been changed.
Big oops, I missed it. In the message editor for new message or replies (on my old CentOS 7 installation)
Insert menu blah blah blah blah Custom header blah blah blah blah
And a slightly different position in the Insert menu on my Fedora 40 installation, so I suspect it's still there in newer releases.
Click on the custom header menu item, and a window pops up
Email Custom Header Security Personal Unclassified Protected Confidential Secret Top Secret None
On a whim, I picked "unclassified" for this reply, to see what it does, and if it makes it through the list server.
Tim:
I suspect it's merely a label and application-specific. The moment you email someone without the requisite software it's going to get ignored.
Stephen Morris:
Organisations, if they so desire, can put processes in place to handle mails with headers specifying sensitivity differently to mails that don't have the headers. In fact, I'm trying to get a defect resolved at the moment where somewhere between the code I wrote to send the mail and the mail arriving in Outlook 365, the sensitivity level in the headers has been changed.
I think you'd have to have a custom mail server to enforce things. For enforcing you have to take control out of the hands of clients.
Big oops, I missed it. In the message editor for new message or replies (on my old CentOS 7 installation)
Insert menu blah blah blah blah Custom header blah blah blah blah
And a slightly different position in the Insert menu on my Fedora 40 installation, so I suspect it's still there in newer releases.
Click on the custom header menu item, and a window pops up
Email Custom Header Security Personal Unclassified Protected Confidential Secret Top Secret None
On a whim, I picked "unclassified" for this reply, to see what it does, and if it makes it through the list server.
On Fri, 2025-03-21 at 16:28 +1030, Tim via users wrote:
On a whim, I picked "unclassified" for this reply, to see what it does, and if it makes it through the list server.
I see it does. It added a header "Security: Unclassified". But for you to know anything about this while reading your mail, you will have to configure
Evolution preferences mail preferences headers
And add "Security" to the list of displayed message headers.
And, you need to have the basic amount of headers (to, from, date, subject, etc,) showing when you read the message. Or open the message in its own window.
If you collapse the message headers down to a single truncated line above the message (just showing "subject" and "from"), in three-pane view, you get no clue about security status, nor any other headers.
It's not readily apparent, and you have to configure things to see it. Perhaps if you customise the GUI it might be possible to show a security header more boldly. It's the kind of thing that should be prominent, not hidden.
Customising the GUI's done by hand-customising some XML files. I did that ages ago to add a filter button to the tool bar to manually apply filters to the current message.
I modified /usr/share/evolution/ui/evolution-mail-reader.ui (that's the main toolbar for the program). There may be some way to add a security status display to be always present in some obvious spot.
The actual headers you can insert into messags seems to be controlled from:
/usr/share/glib-2.0/schemas/org.gnome.evolution.plugin.email-custom-header.gschema.xml
<?xml version="1.0" encoding="UTF-8"?> <schemalist> <schema path="/org/gnome/evolution/plugin/email-custom-header/" id="org.gnome.evolution.plugin.email-custom-header" gettext-domain="evolution"> <key type="as" name="custom-header"> <default>['Security=Personal;Unclassified;Protected;InConfidence;Secret;Topsecret']</default> <summary>List of Custom Headers</summary> <description>The key specifies the list of custom headers that you can add to an outgoing message. The format for specifying a Header and Header value is: Name of the custom header followed by “=” and the values separated by “;”</description> </key> </schema> </schemalist>
On Fri, 2025-03-21 at 16:26 +1030, Tim via users wrote:
On a whim, I picked "unclassified" for this reply, to see what it does, and if it makes it through the list server.
It came through the list with the header.
However, if I reply to such a classified (of some kind) message, the reply will not have the security header unless I deliberately add one while replying. And you'd be unaware of this when replying.
C minus, needs more thought.
On Fri, Mar 21, 2025 at 2:43 AM Tim via users users@lists.fedoraproject.org wrote:
On Fri, 2025-03-21 at 16:26 +1030, Tim via users wrote:
On a whim, I picked "unclassified" for this reply, to see what it does, and if it makes it through the list server.
It came through the list with the header.
However, if I reply to such a classified (of some kind) message, the reply will not have the security header unless I deliberately add one while replying. And you'd be unaware of this when replying.
C minus, needs more thought.
Not copying previous headers is usually a good strategy. Consider the case of the Expires: header in marketing email,[1] indicating when a message should be hidden by the UA or deleted by the server. You would not want a reply to be hidden based on an old Expires: header.
And a more interesting use case (to me)... what happens when a sender's UA specifies one Security: header, and the receiver's server adds a different Security: header? What does the receiver's UA display?
[1] https://mailarchive.ietf.org/arch/msg/mailmaint/MgtSuOJFfgWbTFuAZjGwXNDMcqo/
Jeff
Tim:
However, if I reply to such a classified (of some kind) message, the reply will not have the security header unless I deliberately add one while replying. And you'd be unaware of this when replying.
C minus, needs more thought.
Jeffrey Walton:
Not copying previous headers is usually a good strategy. Consider the case of the Expires: header in marketing email,[1] indicating when a message should be hidden by the UA or deleted by the server. You would not want a reply to be hidden based on an old Expires: header.
Yes, and no... It depends on the header and its purpose.
I remember in my early days of the internet, Outlook Express was widely despised for breaking threading by not including the necessary headers in the replies to maintain the chain. It just, VERY DUMBLY, grouped messages with same subject, but didn't thread replies with their prior message in any sane order.
And I think if you were replying to a secret or confidential message that the classification should stay the same until someone deemed it should be deliberately changed.
I think that NOT behaving that way would get Evolution vetoed as a viable mail client in a sensitive organisation (pun intended).
And a more interesting use case (to me)... what happens when a sender's UA specifies one Security: header, and the receiver's server adds a different Security: header? What does the receiver's UA display?
[1] https://mailarchive.ietf.org/arch/msg/mailmaint/MgtSuOJFfgWbTFuAZjGwXNDMcqo/
Different kettle of fish.
I get marketing mail from various things (electronics shops I've bought products from), that I semi-tolerate. They have special offers with expiry dates. It would be useful if the messages could programatically be assessed for that.
I could see a situation with a few status flags just above each message for "Expired" & "Confidential" in the same way we get PGP/GPG "signature valid"
And the chance to set a few rules to suit myself. Click on the EXPIRED flag on a marketing mail, and trash it. Click on an EXPIRED flag on non-marketing mail and archive it. Or even periodically review the inbox automatically and perform those actions on expired mail for me (according to *my* rules).
At the moment Evolution is displaying a big red banner above the list of mail in the current folder warning me that it can't connect to the contacts list in a gmail account. To me that's NOT a red flag occasion. But I would suggest that the current email being a top secret or confidential one should be. Bold and brassy banner for emails you must use due care with, down to calmer looking banners for unclassified or none.
It's easy to suffer from information overload with email. But if you work somewhere where such status are important, then you should have some way to make them always be seen.
On Fri, 2025-03-21 at 16:56 +1030, Tim via users wrote:
The actual headers you can insert into messags seems to be controlled from:
/usr/share/glib-2.0/schemas/org.gnome.evolution.plugin.email-custom-header.gschema.xml
<?xml version="1.0" encoding="UTF-8"?>
<schemalist> <schema path="/org/gnome/evolution/plugin/email-custom-header/" id="org.gnome.evolution.plugin.email-custom-header" gettext-domain="evolution"> <key type="as" name="custom-header"> <default>['Security=Personal;Unclassified;Protected;InConfidence;Secret;Topsecret']</default> <summary>List of Custom Headers</summary> <description>The key specifies the list of custom headers that you can add to an outgoing message. The format for specifying a Header and Header value is: Name of the custom header followed by “=” and the values separated by “;”</description> </key> </schema> </schemalist>
This custom header is a plug-in, and the plug-in manager does let you edit the options without having to hand-edit the XML file. But if you were customising Evolution for a whole organisation, you probably would want to create custom override XML files.
On Sat, 2025-03-22 at 01:00 +1030, Tim via users wrote:
I remember in my early days of the internet, Outlook Express was widely despised for breaking threading by not including the necessary headers in the replies to maintain the chain. It just, VERY DUMBLY, grouped messages with same subject, but didn't thread replies with their prior message in any sane order.
Threading based on the Subject line is fundamentally broken. Well-run mailing lists use List-* and In-Reply-To headers to keep things straight. Unfortunately many MUAs either don't respect these or don't encourage list users to use them, and once the header chain is broken it can't be re-joined, i.e. if someone uses Reply-To-All instead of Reply-To-List then nothing following that reply will have the correct headers. Evolution has a Group Reply button which tries to Do The Right Thing whenever possible.
poc
Tim:
I remember in my early days of the internet, Outlook Express was widely despised for breaking threading by not including the necessary headers in the replies to maintain the chain. It just, VERY DUMBLY, grouped messages with same subject, but didn't thread replies with their prior message in any sane order.
Patrick O'Callaghan:
Threading based on the Subject line is fundamentally broken. Well-run mailing lists use List-* and In-Reply-To headers to keep things straight.
And the "references" headers. The in-reply-to headers only associate one reply to the message it replied to. The references header is needed to group all the associated messages together.
Unfortunately many MUAs either don't respect these or don't encourage list users to use them, and once the header chain is broken it can't be re-joined
I'm beginning to wonder how many people actually use a mail program instead of a webmail interface these days.
On Sun, 2025-03-23 at 01:36 +1030, Tim via users wrote:
Tim:
I remember in my early days of the internet, Outlook Express was widely despised for breaking threading by not including the necessary headers in the replies to maintain the chain. It just, VERY DUMBLY, grouped messages with same subject, but didn't thread replies with their prior message in any sane order.
Patrick O'Callaghan:
Threading based on the Subject line is fundamentally broken. Well-run mailing lists use List-* and In-Reply-To headers to keep things straight.
And the "references" headers. The in-reply-to headers only associate one reply to the message it replied to. The references header is needed to group all the associated messages together.
Yes, I should have remembered those;
Unfortunately many MUAs either don't respect these or don't encourage list users to use them, and once the header chain is broken it can't be re-joined
I'm beginning to wonder how many people actually use a mail program instead of a webmail interface these days.
Outside of mailing lists such as this one, probably not that many, and those are dominated by the corporate use of Outlook, which is why Evolution supports connections to Exchange (I think Thunderbird does as well). I use the Gmail web interface for a lot of things myself, but I keep Evo for good list handling and sane management of quoting in replies among other things.
poc
Tim:
I'm beginning to wonder how many people actually use a mail program instead of a webmail interface these days.
Patrick O'Callaghan:
Outside of mailing lists such as this one, probably not that many, and those are dominated by the corporate use of Outlook, which is why Evolution supports connections to Exchange (I think Thunderbird does as well). I use the Gmail web interface for a lot of things myself, but I keep Evo for good list handling and sane management of quoting in replies among other things.
I've yet to come across a webmail interface that doesn't suck. I'm not impressed by Gmail's cluttered system, it's worse than what I remember of Hotmail a quarter of a century ago.
It was a ridiculous palaver just to find a way to send a new email to a person without it being a reply, for instance.
On Tue, 2025-03-25 at 11:30 +1030, Tim via users wrote:
Tim:
I'm beginning to wonder how many people actually use a mail program instead of a webmail interface these days.
Patrick O'Callaghan:
Outside of mailing lists such as this one, probably not that many, and those are dominated by the corporate use of Outlook, which is why Evolution supports connections to Exchange (I think Thunderbird does as well). I use the Gmail web interface for a lot of things myself, but I keep Evo for good list handling and sane management of quoting in replies among other things.
I've yet to come across a webmail interface that doesn't suck. I'm not impressed by Gmail's cluttered system, it's worse than what I remember of Hotmail a quarter of a century ago.
Years ago there used to be a feature under Gmail Labs where you could get sensible quoting and avoid top-posting. It worked for me, but has since been removed.
It was a ridiculous palaver just to find a way to send a new email to a person without it being a reply, for instance.
Clicking on the address works.
poc
*From:* Samuel Sieb samuel@sieb.net
*Sent:* Friday, 21 March 2025 at 09:20 UTC+11
*To:* users@lists.fedoraproject.org
*Subject:* RE: Evolution Functionality
On 3/20/25 2:53 PM, Stephen Morris wrote:
*From:* Samuel Sieb samuel@sieb.net *Sent:* Thursday, 20 March 2025 at 09:49 UTC+11 *To:* users@lists.fedoraproject.org *Subject:* RE: Evolution Functionality
On 3/19/25 3:11 PM, Stephen Morris wrote:
I have a query about the functionality of Evolution as a mail package. Does Evolution support the tagging of outgoing mails as "organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
Do you have an example of an email client that supports automatically tagging outgoing email? Thunderbird can certainly tag incoming emails according to headers.
Thunderbird does not have any support for mail headers tagging sensitivity levels, nor does it provide the ability to actually tag a mail as sensitive. I've seen an article on the net that was saying a request for that functionality has been outstanding for, I think it said, 12 years.
What does that even mean? What effect would "tagging a sensitivity level" have? You didn't answer my first question. Do you have an example of an email client that does what you want?
Outlook does have the ability to tag emails as confidential or private, which it does by inserting mail headers into the existing mail headers. The environment I program in has the ability to send emails tagged as confidential or private and it does the flagging the same way as outlook does, and that environment can perform that functionality under both windows and linux. I was trying to check if Evolution can do the same thing because I am trying to investigate a defect in the environment where I work.
Does Evolution, when setting up the mail interface, provide the functionality to auto configure the mail server definitions or do you have to set them up manually?
Does your domain have that configured?
When I was using the email address provided by my isp, and using a gmail address, both environments provide Thunderbird with the ability to auto define the mail servers irrespective of whether you want to use IMAP or POP3.
Ok, but you're referring to some other environment. gmail and your ISP probably have the automatic config information available. But does your environment?
That depends on what you mean by "my environment". Thunderbird running locally on my machine will auto configure the mail servers when I supply the email address for the account I want to define in Thunderbird, so I was querying if Evolution can do the same thing? regards, Steve
*From:* Jeffrey Walton noloader@gmail.com
*Sent:* Friday, 21 March 2025 at 10:34 UTC+11
*To:* Community support for Fedora users users@lists.fedoraproject.org
*Subject:* RE: Evolution Functionality
On Thu, Mar 20, 2025 at 6:22 PM Samuel Siebsamuel@sieb.net wrote:
On 3/20/25 2:53 PM, Stephen Morris wrote:
*From:* Samuel Siebsamuel@sieb.net
*Sent:* Thursday, 20 March 2025 at 09:49 UTC+11
*To:*users@lists.fedoraproject.org
*Subject:* RE: Evolution Functionality
On 3/19/25 3:11 PM, Stephen Morris wrote:
I have a query about the functionality of Evolution as a mailpackage.
Does Evolution support the tagging of outgoing mails as"organisation-sensitive" and hence generate the appropriate mail headers, and conversely, when an email comes in with mail headers specifying a sensitivity level does Evolution tag the mail appropriately?
Do you have an example of an email client that supports automatically tagging outgoing email? Thunderbird can certainly tag incoming emails according to headers.
Thunderbird does not have any support for mail headers tagging sensitivity levels, nor does it provide the ability to actually tag a mail as sensitive. I've seen an article on the net that was saying a request for that functionality has been outstanding for, I think it said, 12 years.
What does that even mean? What effect would "tagging a sensitivity level" have? You didn't answer my first question. Do you have an example of an email client that does what you want?
I'm not speaking for Stephen... But Microsoft supports sensitivity levels in Office 365. See https://support.microsoft.com/en-us/office/apply-sensitivity-labels-to-your-files-2f96e7cd-d5a4-403b-8bd7-4cc636bae0f9.
For general email, I believe you can use the Sensitivity: email header from RFC 1327. Or maybe use an X-header.
The BNF for RFC 1327 Sensitivity: is kind of lame:
sensitivity = "Personal" / "Private" / "Company-Confidential"So I would expect to see modern mail user agents use the X-headers to express finer grain classification.
Outlook in Office 365 uses the above tags for sensitivity and the environment I programme in does as well, although it uses "none" / "Private" / "Confidential" / "Company-Confidential" (which is what Outlook uses for "Confidential") although that environment says that "Confidential" and "Company-Confidential" are the same thing and I thought it was quoting a different RFC for compatibility with in supplying "Company-Confidential", and like Outlook if "Confidential" is specified it replaces that with "Company-Confidential". regards, Steve
Does Evolution, when setting up the mail interface, provide thefunctionality to auto configure the mail server definitions or do you have to set them up manually?
Does your domain have that configured?
When I was using the email address provided by my isp, and using a gmail address, both environments provide Thunderbird with the ability to auto define the mail servers irrespective of whether you want to use IMAP or POP3.
Ok, but you're referring to some other environment. gmail and your ISP probably have the automatic config information available. But does your environment?
Jeff
*From:* Tim via users users@lists.fedoraproject.org
*Sent:* Saturday, 22 March 2025 at 01:40 UTC+11
*To:* users@lists.fedoraproject.org
*Cc:* Tim ignored_mailbox@yahoo.com.au
*Subject:* RE: Evolution Functionality
On Fri, 2025-03-21 at 16:56 +1030, Tim via users wrote:
The actual headers you can insert into messags seems to be controlled from:
/usr/share/glib-2.0/schemas/org.gnome.evolution.plugin.email-custom-header.gschema.xml
<?xml version="1.0" encoding="UTF-8"?>
<schemalist> <schema path="/org/gnome/evolution/plugin/email-custom-header/" id="org.gnome.evolution.plugin.email-custom-header" gettext-domain="evolution"> <key type="as" name="custom-header"> <default>['Security=Personal;Unclassified;Protected;InConfidence;Secret;Topsecret']</default> <summary>List of Custom Headers</summary> <description>The key specifies the list of custom headers that you can add to an outgoing message. The format for specifying a Header and Header value is: Name of the custom header followed by “=” and the values separated by “;”</description> </key> </schema> </schemalist>
This custom header is a plug-in, and the plug-in manager does let you edit the options without having to hand-edit the XML file. But if you were customising Evolution for a whole organisation, you probably would want to create custom override XML files.
If a mail header specifies a sensitivity level, when the mail is read in Outlook it adds a message above the subject to treat the mail as whatever sensitivity is specified (except if there is no sensitivity, in which case the sensitivity header is absent). regards, Steve
*From:* Patrick O'Callaghan pocallaghan@gmail.com
*Sent:* Saturday, 22 March 2025 at 03:59 UTC+11
*To:* users@lists.fedoraproject.org
*Subject:* RE: Evolution Functionality
On Sat, 2025-03-22 at 01:00 +1030, Tim via users wrote:
I remember in my early days of the internet, Outlook Express was widely despised for breaking threading by not including the necessary headers in the replies to maintain the chain. It just, VERY DUMBLY, grouped messages with same subject, but didn't thread replies with their prior message in any sane order.
Threading based on the Subject line is fundamentally broken. Well-run mailing lists use List-* and In-Reply-To headers to keep things straight. Unfortunately many MUAs either don't respect these or don't encourage list users to use them, and once the header chain is broken it can't be re-joined, i.e. if someone uses Reply-To-All instead of Reply-To-List then nothing following that reply will have the correct headers. Evolution has a Group Reply button which tries to Do The Right Thing whenever possible.
poc
Thunderbird is similar in that for mails I receive from this list the "Reply All" button is replaced by "Reply List", and if by mistake I press "Reply" it expectedly breaks the chain. regards, Steve
*From:* Tim via users users@lists.fedoraproject.org
*Sent:* Sunday, 23 March 2025 at 02:06 UTC+11
*To:* Community support for Fedora users users@lists.fedoraproject.org
*Cc:* Tim ignored_mailbox@yahoo.com.au
*Subject:* RE: Evolution Functionality
Tim:
I remember in my early days of the internet, Outlook Express was widely despised for breaking threading by not including the necessary headers in the replies to maintain the chain. It just, VERY DUMBLY, grouped messages with same subject, but didn't thread replies with their prior message in any sane order.
Patrick O'Callaghan:
Threading based on the Subject line is fundamentally broken. Well-run mailing lists use List-* and In-Reply-To headers to keep things straight.
And the "references" headers. The in-reply-to headers only associate one reply to the message it replied to. The references header is needed to group all the associated messages together.
Unfortunately many MUAs either don't respect these or don't encourage list users to use them, and once the header chain is broken it can't be re-joined
I'm beginning to wonder how many people actually use a mail program instead of a webmail interface these days.
Where I work everybody uses a mail client, and we only use the web interface for checking issues in the client, and even though the organisation has switched to Outlook/Exchange there are still areas of the business that still using Lotus Notes/Domino. regards, Steve
Tim:
It was a ridiculous palaver just to find a way to send a new email to a person without it being a reply, for instance.
Patrick O'Callaghan:
Clicking on the address works.
It hid them...
I had a series of separate emails I've sent someone, who responded outside of email, so they're sitting by themselves in the sent box. They're not a thread, but gmail is bunching them together because of a common recipient. I could see a name of the recipient, but no address, and nothing obvious to click on until I delved into them.
All-in-all, a right pig's breakfast of a user-interface.
On Wed, 2025-03-26 at 09:24 +1100, Stephen Morris wrote:
Thunderbird is similar in that for mails I receive from this list the "Reply All" button is replaced by "Reply List", and if by mistake I press "Reply" it expectedly breaks the chain. regards, Steve
Evolution has noticed a mailing-list header, and if I just just ordinary reply, I get double-prompted about replying privately or to the list.
I think few ordinary users participate in lists, now. It's all (anti)social-media sites.
On Wed, 2025-03-26 at 09:19 +1100, Stephen Morris wrote:
If a mail header specifies a sensitivity level, when the mail is read in Outlook it adds a message above the subject to treat the mail as whatever sensitivity is specified (except if there is no sensitivity, in which case the sensitivity header is absent). regards, Steve
This is something missing from Evolution. To see any hint about sensitivity, you have to configure the user-agent to show a header, and then it just shows you the raw text that got added after the header.
If you were sending and receiving confidential messages, there ought to be a prominent indicator (there isn't), and replies ought to maintain the security level unless you deliberately change it (it doesn't, the replies have no security level unless you add one).
On Wed, 2025-03-26 at 09:08 +1100, Stephen Morris wrote:
Thunderbird running locally on my machine will auto configure the mail servers when I supply the email address for the account I want to define in Thunderbird, so I was querying if Evolution can do the same thing? regards, Steve
There's a variety of ways that can be done with mail clients, I knew of these three:
It can make guesses about mail server names based on the domain name of the email address you're setting up. Evolution did not appear to do this when I tried just now.
It can poll a well-known address associated with the domain name of the email address, for a config file. I recall Evolution did appear to support this method, I've done it in my own LAN, though it doesn't appear to be working when I've just double-checked now. But I may have mangled something in my network at the moment.
It can poll a central configuration service which is populated with data about a plethora of mail services. This is a method that Thunderbird can use (they have their own configuration server, and Evolution will look at it).
This is what /they/ say about it: https://wiki.gnome.org/Apps(2f)Evolution(2f)Autoconfig.html
And this suggests yet another scheme: https://wiki.gnome.org/Apps(2f)Evolution(2f)AutoconfigSources.html
In a nutshell, I'd say that's a sysadmin for your local computer system dropping a configuration file into the users homespace.
On Wed, 2025-03-26 at 12:01 +1030, Tim via users wrote:
On Wed, 2025-03-26 at 09:24 +1100, Stephen Morris wrote:
Thunderbird is similar in that for mails I receive from this list the "Reply All" button is replaced by "Reply List", and if by mistake I press "Reply" it expectedly breaks the chain. regards, Steve
Evolution has noticed a mailing-list header, and if I just just ordinary reply, I get double-prompted about replying privately or to the list.
I think few ordinary users participate in lists, now. It's all (anti)social-media sites.
Even the Gnome project has moved many of its mailing lists to the dreadful Discourse online system, including the original Evolution list (there's some irony for you) which is why some of us created a new list for the purpose.
poc
*From:* Tim via users users@lists.fedoraproject.org
*Sent:* Wednesday, 26 March 2025 at 12:57 UTC+11
*To:* Community support for Fedora users users@lists.fedoraproject.org
*Cc:* Tim ignored_mailbox@yahoo.com.au
*Subject:* RE: Evolution Functionality
On Wed, 2025-03-26 at 09:08 +1100, Stephen Morris wrote:
Thunderbird running locally on my machine will auto configure the mail servers when I supply the email address for the account I want to define in Thunderbird, so I was querying if Evolution can do the same thing? regards, Steve
There's a variety of ways that can be done with mail clients, I knew of these three:
It can make guesses about mail server names based on the domain name of the email address you're setting up. Evolution did not appear to do this when I tried just now.
It can poll a well-known address associated with the domain name of the email address, for a config file. I recall Evolution did appear to support this method, I've done it in my own LAN, though it doesn't appear to be working when I've just double-checked now. But I may have mangled something in my network at the moment.
It can poll a central configuration service which is populated with data about a plethora of mail services. This is a method that Thunderbird can use (they have their own configuration server, and Evolution will look at it).
This is what /they/ say about it: https://wiki.gnome.org/Apps(2f)Evolution(2f)Autoconfig.html
And this suggests yet another scheme: https://wiki.gnome.org/Apps(2f)Evolution(2f)AutoconfigSources.html
In a nutshell, I'd say that's a sysadmin for your local computer system dropping a configuration file into the users homespace.
Thankyou, I'll check this out. I'm trying to find a mail package that supports sensitivity headers, that will leave the mail on the remote server in a form that thunderbird can still download so that I don't lose them (I might be able to flag them as unread in gmail, but I need to check), so that I can investigate an issue at work where external emails tagged as sensitive don't make the inbox of a shared mailbox in Outlook but they do make the inbox of personal mailboxes, but if I use the Office 365 mail web interface the sensitive emails do make the inbox of the shared mailbox. If I send an email from my personal mailbox to the shared mailbox that I have flagged as sensitive from Outlook (which as far as I can see is specifying the same headers as the program I wrote to send the mail) the mail does make the inbox of the shared mailbox. Because of all this the admins are saying that the mail environment is working correctly therefore they cannot provide any assistance to resolve the issue. I'm also seeing headers provided by an application the organisation is using to "protect" the mail system from external mails, that are saying the mail source has not been specified in the organisations domain as a permitted mail source, but I see those messages in both sensitive and non-sensitive mails that make it to the personal mailboxes, so I'm not sure yet what they mean, and the admins are ignoring those messages, hence I'm trying to send a sensitive mail from home to see what happens with that, which is why I'm looking at Evolution functionality because Thunderbird doesn't support sensitivity options. I've just also tried this from the gmail web interface, where gmail can tag a mail as confidential and specify an expiry date for the mail, where it is saying the recipient cannot forward, copy, print or download the email. regards, Steve
*From:* Tim via users users@lists.fedoraproject.org
*Sent:* Wednesday, 26 March 2025 at 12:38 UTC+11
*To:* Community support for Fedora users users@lists.fedoraproject.org
*Cc:* Tim ignored_mailbox@yahoo.com.au
*Subject:* RE: Evolution Functionality
On Wed, 2025-03-26 at 09:19 +1100, Stephen Morris wrote:
If a mail header specifies a sensitivity level, when the mail is read in Outlook it adds a message above the subject to treat the mail as whatever sensitivity is specified (except if there is no sensitivity, in which case the sensitivity header is absent). regards, Steve
This is something missing from Evolution. To see any hint about sensitivity, you have to configure the user-agent to show a header, and then it just shows you the raw text that got added after the header.
If you were sending and receiving confidential messages, there ought to be a prominent indicator (there isn't), and replies ought to maintain the security level unless you deliberately change it (it doesn't, the replies have no security level unless you add one).
With sensitive mails in Outlook, if you forward the mail Outlook retains the mail headers in the forwarded mail and honours the headers. With the issue I'm trying to resolve of a sensitive mail not making the inbox of a shared mailbox but making the inbox of a personal mailbox (my mailbox), if I forward the sensitive mail from my mailbox to the shared mailbox the forwarded mail never makes the shared mailbox either. regards, Steve
On Thu, 2025-03-27 at 09:15 +1100, Stephen Morris wrote:
With sensitive mails in Outlook, if you forward the mail Outlook retains the mail headers in the forwarded mail and honours the headers.
I'd expect that. Forward generally means pass it along as-it-is (that's if you pass it along as an attachment). If it just creates a new email with the original message pasted into it, I wouldn't know what to expect it to do with the headers, though ignoring them springs to mind as the most obvious behaviour.
Replying to an email is another matter. Only the headers pertinent to maintaining a thread would carry over, and any other headers that ought to, too. All the ones that shouldn't, are not (such as all the servers the original past through before you got it).
Since putting sensitivity headers into a message is being done by a plug-in with Evolution, the main program doesn't know anything about them, so ignores them.
On Thu, 2025-03-27 at 09:08 +1100, Stephen Morris wrote:
I'm trying to find a mail package that supports sensitivity headers, that will leave the mail on the remote server in a form that thunderbird can still download so that I don't lose them (I might be able to flag them as unread in gmail, but I need to check)
If the server has IMAP, then Evolution leaves messages them where they are, and just has a local cache (like web browser caching) that speeds up re-opening the same message if you go back and forth. It also can treat Gmail's mail protocol the same way. And local mailbox, MH-format or maildir files.
As far as I'm aware, all Evolution will do is change the been-read status, if all you're doing with the messages is reading them, which you can easily change back. Or you can set Evolution not see automatically set a read status (you'd have to manually do so).
so that I can investigate an issue at work where external emails tagged as sensitive don't make the inbox of a shared mailbox in Outlook but they do make the inbox of personal mailboxes, but if I use the Office 365 mail web interface the sensitive emails do make the inbox of the shared mailbox. If I send an email from my personal mailbox to the shared mailbox that I have flagged as sensitive from Outlook (which as far as I can see is specifying the same headers as the program I wrote to send the mail) the mail does make the inbox of the shared mailbox. Because of all this the admins are saying that the mail environment is working correctly therefore they cannot provide any assistance to resolve the issue. I'm also seeing headers provided by an application the organisation is using to "protect" the mail system from external mails, that are saying the mail source has not been specified in the organisations domain as a permitted mail source, but I see those messages in both sensitive and non-sensitive mails that make it to the personal mailboxes, so I'm not sure yet what they mean, and the admins are ignoring those messages, hence I'm trying to send a sensitive mail from home to see what happens with that, which is why I'm looking at Evolution functionality
Well, there's more than one header that can be used with sensitivity headers, but probably only one that has some official standing. Depending on which mail client you play with, it may pay attention to different ones.
With Evolution, like most mail clients, you can view the source and look at all the headers. Though that's a lot. You can configure specific headers to be shown with the normal mail view, and it'll show them if they exist, and not waste any space if they don't. There you could add these, and any others you find out about:
Security Sensitivity x-protective-marking x-original-protective-marking x-classifier
The top two just appears to have plain text words describing the mail, and appear to be the same thing as each other. I've used Evolution to set Security header to "unclassified" on this message.
The next two have more data in them, aren't particularly user-friendly to read, probably only intended for machine interpretation.
I think the last one is just for the name of the software they used (janusSEAL for Outlook 2.6.2). It didn't have any other data in it.
There may be other security-related headers for this kind of thing, but I don't have any other examples to examine. The documentation I've found so far discusses how to use the software, not what it actually does to the message.
If you look up email security headers, you tend to find the ones associated with encryption, messages signatures, and anti-fraud domain signatures.
Looking at mail clients with security setting options, there's things like classification levels, *and* identifying the people allowed to read it ("confidential", "all staff", kind of of thing). So I'd expect there to be another (unknown) header to list the authorised groups.
https://www.iana.org/assignments/message-headers/message-headers.xhtml Lists well known standardised headers, I don't know if there will be any useful documentation, anywhere, for the headers peculiar to particular software.
You might have to create some new messages with varying security header choices, and look for what headers they add to the mail. You probably won't have to post, just save a draft and view the source of the draft. That'll also help in there being less headers to trawl through, as it won't have gone through any mail servers.
If your problem is with a specific client or server, is there an anti- spam filter that's bad? Are your missing mails being junked?
Is the user in question a low-status person not allowed to read certain sensitive mails and being automatically censored?
On an operational level, considering the varying support for this, and that people could use any mail client that you don't know about to read messages, security warnings should also be printed in the body text at the top of the message. Emails I received from a government body added some text to the end of the subject line to cover that issue, but didn't take into account long subject lines pushing that text off the edge and out of view.