[Mailman-Developers] mm-handler 2.1.10 (was:beforenextrelease:disable backscatter in default installation)

[Kenneth Porter]

--On Saturday, March 29, 2008 9:37 AM -0700 Mark Sapiro <mark at msapiro.net> 
wrote:

> I just checked, and my CentOS 5 system only has Sys::Syslog and not
> Unix::Syslog. It might be worthwhile to provide your version plus a
> patch to go back to the old DEBUG w/o logging. OTOH, Unix::Syslog is
> available from CPAN, DAG, etc., so I don't think it's unreasonable to
> expect people to be able to get it.

I've got perl-Unix-Syslog-1.0-1.el5.rf installed from RPMForge. There's a 
page in the CentOS wiki that explains how to enable this yum/RPM repository.

> I have another question since I don't know sendmail. Does sendmail
> execute mm-handler at incoming SMTP time, and if so, does an error
> exit from mm-handler result in an SMTP failure status being returned
> to the sending MTA?

Correct. mm-handler is a "mailer" which is invoked upon receipt by 
sendmail, which typically happens via SMTP. (Sendmail can also accept mail 
via local socket, or by direct invocation.) It's expected to return a value 
from /usr/include/sysexits.h. Most Red Hat, Fedora and CentOS users know 
the procmail mailer, as it's used for local delivery. Based on properties 
of a message, another mailer may be chosen, either from the config file or 
from the mailertable map file. The mm-handler README explains how to set up 
a match on the domain name.

> If so, it seems that rather than just dropping a 'bad' message as
> mm-handler seems to do when $BounceUnapproved = 0; and $BounceNonlist
> = 0;, wouldn't it be better to exit with a failure status.

Good idea. EX_NOUSER (67) would be a good code to return. Does Perl have a 
module that defines these codes symbolically? I didn't see anything at 
CPAN, but I found one here:

<http://pub.ks-and-ks.ne.jp/prog/SysExits.shtml>