[Mailman-Developers] MM 3 and Postfix + Apache

[Stephen J. Turnbull]

Tom Browder writes:
 > On Thu, Mar 6, 2014 at 1:36 PM, Stephen J. Turnbull <stephen at xemacs.org> wrote:
 > > Barry Warsaw writes:
 > >  > BTW Tom, are you trying to run MM2 and MM3 concurrently?  I'd like
 > > I do this already, but with Exim4 as MTA.  It's not hard.  Of course
 > > if both installations have lists of the same name (including the
 > 
 > There will not be any identical names, so maybe doable fairly easily
 > with Postfix?

Yeah, I suppose so.  I don't recall how Postfix does the dispatching.

Exim basically has a chain of what it calls "routers", which look at
the message and metadata (the envelope addressee's mailbox is what I
use), apply other tests (checking for the list's config pickle is what
I use, but it would be possible to query a database or even call out
to the Mailman3 REST API -- probably a bad idea, since if Mailman is
down, the router will fail, but possible), and dispatch the message to
a transport for delivery (piping to the Mailman program).  Routers are
"first full match wins", so it's quite easy to understand the logic.
In particular, a "one host, multiple Mailman installations" setup
requires just one router per Mailman installation.  The router's check
for a file system object is what disambiguates the installations.

Usually Postfix is configured to route mail with a set of sendmail-
like aliases files, so you just define different alias files for each
Mailman installation and configure Postfix to look at them with the
alias_database directive in postfix/main.cf.  I guess Mailman itself
can be used to generate them without much trouble.

What I can't help with on Postfix, and something I suspect Barry will
be concerned with, is virtual domains where dom1 prefers the tried and
true (Mailman2) and dom2 is ready to try something new (Mailman3).  In
Exim this is no harder; the routers just check for the virtual domain
as well as the mailbox and config files.  I don't know how Postfix
would handle this; the alias files only know about mailboxes as far as
I know.  The virtual domains are sorted out by a different mechanism.

Regards,

Steve