F20 Where's my system mail?

[Heinz Diehl]

On 17.04.2014, Timothy Murphy wrote: 

> I found I could only set myorigin and mydestination by experiment;
> I didn't understand the descriptions in main.cf.

With mydestination you specify your local domain(s). Example:

 mydestination = fritha.org

All mail handled by postfix which goes to .fritha.org will be
delivered locally. When there's no local user for it, the mail will be
undeliverable and bounce. Mail to .fritha.org will not be send to the smarthost
or elsewhere. You can say that this postfix is the mail server for
fritha.org.

(For virtual hosting of a domain, you'll have to configure it in the
virtual alias db).

The myorigin parameter defines where your mail is coming
from when you send a mail. Example: you log in as "htd" and write a mail to somebody. With

 myorigin = $mydomain

postfix will append this to your local user as the sender address
(htd at fritha.org).
 
> I would hesitate to follow documentation for another OS.
> I found I had to make several changes when going from CentOS-5 to CentOS-6.

Postfix shoud be the same on all systems.

> I didn't set mynetworks_style because I didn't understand
> the advice in main.cf:

With "host", only mail from the local machine will be
accepted. With "subnet", your whole subnet(s) are valid for sending
mail. "Class" should be taken with caution, because the whole network
class you specify here will be able to send mail via your postfix. You
don't want the whole Alice network to spam the world using your
postfix :-)

> -------------------
> # By default (mynetworks_style = subnet), Postfix "trusts" SMTP
> # clients in the same IP subnetworks as the local machine.

This would be the case for a home network for your family, e.g..

> # On Linux, this does works correctly only with interfaces specified
> # with the "ifconfig" command.
> -------------------
> It seems curious to set a default which is said not to work properly.
> What do you set it to, as a matter of interest?

It depends on your case. Mine is set to 127.0.0.0/8, which means
"localhost only".
> 
> Here are my diffs [line numbers deleted]
[....]

Looks quite standard and ok to me (assuming that some of the
parameters which are listed twice aren't doubled in your main.cf).