I have mailman set up to send mail via an external MTA, which is
supported by mailman and described in the documentation here:
https://docs.mailman3.org/projects/mailman/en/latest/src/mailman/docs/mta.h….
Specifically it says:
|lmtp_host|and|lmtp_port|are parameters which are used by Mailman, but
also will be passed to the MTA to identify the Mailman host. The “same
host” case is special; some MTAs (including Postfix) do not recognize
“localhost”, and need the numerical IP address. If they are on different
hosts,|lmtp_host|should be set to the domain name or IP address of the
Mailman host.|lmtp_port|is fairly arbitrary (there is no standard port
for LMTP). Use any port convenient for your site. “8024” is as good as
any, unless another service is using it.
However, there is a practical problem with LMTP (to receive incoming
email) which is as follows:
The setup in mailman.cfg:
lmtp_host: lists.fast.za.net
lmtp_port: 8024
Now, lists.fast.za.net is the mailman server. The docs say that mailman
passes these on to the MTA. However, the MTA (postfix) on
box2.gtahardware.co.za has the following setting in it main.cf:
virtual_transport=lmtp:[127.0.0.1]:10025
If I reply to a signup confirmation email for example, the mail is
received and processed by box2.gtahardware.co.za, and it is not passed
on to the mailman server.
So what is meant by "but also will be passed to the MTA to identify the
Mailman host" in the docs?
If I change the config of the MTA (postfix) to be
"virtual_transport=lmtp:[lists.fast.za.net]:8024", I assume the incoming
mail will be forwarded, but how does postfix know that only the mailman
emails should be forwarded and not all the other mail that the server at
box2.gtahardware.co.za receives?
This is quite fuzzt to me at this stage. Could someone help me with some
clarity please?
