[BALUG-Admin] mailman-loop ...

Rick Moen rick@linuxmafia.com
Fri Sep 22 11:46:34 PDT 2017

Quoting Michael Paoli (Michael.Paoli@cal.berkeley.edu):

> Mailman bounce processing.  So ... Mailman has per-list bounce
> processing - and aliases that go to pipes for those, e.g:
> balug-test-bounces:      "|/var/lib/mailman/mail/mailman bounces balug-test"
> and I'm presuming those just automagically "do the right thing"...
> soon ... as it's probably not yet right.  :-/
> Also, Debian+exmi4 - by default doesn't allow aliases to go to pipes
> or files.

To pipes, yes.  I don't know what you mean by not to files, in that
destination mbox files are files, and /etc/aliases entries to those
definitely work.  The disabling of processing of pipes in /etc/aliases 
is/was a security improvement, as there have been just far too many
security meltdowns causes by exploits of shell processing in exactly
that area.

In recent mail, I'd assumed that, nonetheless, Exim4 _does_ correctly
process the pipes used in /var/lib/mailman/data/aliases that the
/var/lib/mailman/bin/newlist command adds per-list stanzas to -- but 
I'm just now remembering that /var/lib/mailman/data/aliases is now 
vestigial if you add the recommended Mailman plumbing to Exim4
transports and routers.  (Disclaimer:  This reflects not careful study
but rather yet another super-quick look around.)  

My surmise today is that the Exim4 additions to routers and transports
bypasses the traditional aliases mechanism entirely and makes Exim4 
parse the MAILMAN_HOME/lists/$local_part/config.pck (Python 'pickled' 
format) files for per-list data, instead, probably using the
$MAILMAN_HOME/mail/mailman tools, if my overly-quick parsing of Exim4's
conffiles is correct.

In which case, sorry about the digression onto a vestigial file.  That's
the problem with having run this stuff since dinosaur days:  You keep
wanting to maintain stuff that's actually not used any more, but in many
cases is confusingly still around anyway.

(FWIW, I'd also noticed that /var/lib/mailman/data/owner-bounces.mbox is
non-existent on my system, but had overhastily written that fact off as 
merely indicating that it was getting cleaned out or something.)

> So, ... like I say, will need to review/fix ... and soon.
> Thanks for mentioning it, etc. - covered some of my questions,
> and I wasn't aware of the /var/lib/mailman/data/aliases file.

Probably vestigial, on second thought.  My current guess.

Moving on...

Given your empirical observation that inbound mail to  mailman-loop was 
bouncing, that raises the subsidiary question of how it _ought_ to be
directed.  Sending it to root/postmaster via /etc/aliases of course
ensures that it goes somewhere, but is it where it _should_ go?  I'm
really not sure.  Maybe you should ask the Mailman and/or Exim experts.

> VERP :-) ... yeah, I'd forgotten what it was called, but recalled
> reading about it in Mailman configuration stuff.  And yes,
> advantages/disadvantages ... but can be quite good for better
> processing of bounces and backscatter.  So, yeah, may be better
> on balance, to enable it, than not ... or maybe at least
> occasionally/periodically enable it.  Ah, but should probably
> first get mailman-loop working as it ought.

VERP will let you find the problem child.  Enable it for that, and you
can disable it after you track that subscriber down.

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