Error in "Use Postfix to get email from your Fedora system"

[Gregory Bartholomew]

It looks like an error may have been introduced during the editing of the
"Use Postfix" article.

I think the values used in password_maps file and the main.cf file need to
match. Otherwise "WantAuthError" shows up in the logs:

Aug 03 12:12:57 eb2027-01.cs.siue.edu postfix/smtp[8960]: 11DFB19523: to=<
[e-mail]>, relay=smtp.gmail.com[74.125.69.109]:587,
delay=0.39, delays=0.03/0.04/0.3/0.02, dsn=5.5.1, status=bounced (host
smtp.gmail.com[74.125.69.109] said: 530-5.5.1 Authentication Required.
Learn more at 530 5.5.1  https://support.google.com/mail/?p=WantAuthError
f17sm75891337ioc.2 - gsmtp (in reply to MAIL FROM command))

I had used "[smtp.gmail.com]:587" in both places because smtp.gmail.com is
an SMTP server, not a domain name against which an MX query should be run.
From the man page:

$ man postconf.5 | grep -A 19 ^relayhost
relayhost (default: empty)
       The next-hop destination of non-local mail; overrides non-local
domains in recipient  addresses.  This  information  is  overruled  with
       relay_transport,  sender_dependent_default_transport_maps,
 default_transport, sender_dependent_relayhost_maps and with the
transport(5)
       table.

On an intranet, specify the organizational domain name. If your
internal DNS uses no MX records, specify the name of the intranet  gate‐
       way host instead.

In  the  case  of  SMTP,  specify a domain name, hostname,
hostname:port, [hostname]:port, [hostaddress] or [hostaddress]:port. The
form
       [hostname] turns off MX lookups.

If you're connected via UUCP, see the UUCP_README file for useful
information.

Examples:

relayhost = $mydomain
       relayhost = [gateway.example.com]
       relayhost = uucphost
       relayhost = [an.ip.add.ress]

Also, the Wikipedia page on MX records points out some limitations with the
MX protocol:

"The MX mechanism does not grant the ability to provide mail service on
alternative port numbers https://en.wikipedia.org/wiki/Port_number, nor
does it provide the ability to distribute mail delivery across a set of
unequal-priority mail servers by assigning a weighting value to each one." (
https://en.wikipedia.org/wiki/MX_record)

So, I think "[smtp.gmail.com]:587" is the proper value. I think other/newer
tricks are used to load balance the smtp.gmail.com DNS name and route
traffic to the nearest/best server and MX lookups should be avoided in this
case. I could be wrong though. I'm not an expert in this field.

gb

[Paul Frields]

I fixed this. Not sure how it got messed up since I only deleted some of
the surrounding stuff we talked about, but should be good now.

On Sat, Aug 3, 2019, 1:30 PM Gregory Bartholomew <
[e-mail]> wrote:
> It looks like an error may have been introduced during the editing of the
> "Use Postfix" article.
>
> I think the values used in password_maps file and the main.cf file need
> to match. Otherwise "WantAuthError" shows up in the logs:
>
> Aug 03 12:12:57 eb2027-01.cs.siue.edu postfix/smtp[8960]: 11DFB19523: to=<
> [e-mail]>, relay=smtp.gmail.com[74.125.69.109]:587,
> delay=0.39, delays=0.03/0.04/0.3/0.02, dsn=5.5.1, status=bounced (host
> smtp.gmail.com[74.125.69.109] said: 530-5.5.1 Authentication Required.
> Learn more at 530 5.5.1  https://support.google.com/mail/?p=WantAuthError
> f17sm75891337ioc.2 - gsmtp (in reply to MAIL FROM command))
>
> I had used "[smtp.gmail.com]:587" in both places because smtp.gmail.com
> is an SMTP server, not a domain name against which an MX query should be
> run. From the man page:
>
> $ man postconf.5 | grep -A 19 ^relayhost
> relayhost (default: empty)
>        The next-hop destination of non-local mail; overrides non-local
> domains in recipient  addresses.  This  information  is  overruled  with
>        relay_transport,  sender_dependent_default_transport_maps,
>  default_transport, sender_dependent_relayhost_maps and with the
> transport(5)
>        table.
>    On an intranet, specify the organizational domain name. If your
>
> internal DNS uses no MX records, specify the name of the intranet  gate‐
>        way host instead.
>    In  the  case  of  SMTP,  specify a domain name, hostname,
>
> hostname:port, [hostname]:port, [hostaddress] or [hostaddress]:port. The
> form
>        [hostname] turns off MX lookups.
>    If you're connected via UUCP, see the UUCP_README file for useful
>
> information.
>    Examples:
>
>    relayhost = $mydomain
>    relayhost = [gateway.example.com]
>    relayhost = uucphost
>    relayhost = [an.ip.add.ress]
>
> Also, the Wikipedia page on MX records points out some limitations with
> the MX protocol:
>
> "The MX mechanism does not grant the ability to provide mail service on
> alternative port numbers https://en.wikipedia.org/wiki/Port_number, nor
> does it provide the ability to distribute mail delivery across a set of
> unequal-priority mail servers by assigning a weighting value to each one." (
> https://en.wikipedia.org/wiki/MX_record)
>
> So, I think "[smtp.gmail.com]:587" is the proper value. I think
> other/newer tricks are used to load balance the smtp.gmail.com DNS name
> and route traffic to the nearest/best server and MX lookups should be
> avoided in this case. I could be wrong though. I'm not an expert in this
> field.
>
> gb

[Gregory Lee Bartholomew]

No worries. Maybe I made the error in the original. What I had on my test system had the brackets though, so I don't think so. Hopefully WordPress isn't auto-removing brackets, but it does still remove leading # characters when I paste stuff into pre-formatted blocks, so I'm not sure that I would rule out that possiblity.

Anyway, thanks for fixing it.