Hi mailman developers. Another suggestion, apologies if this is already implemented in a newer version... if there is a permission error or other exception thrown which prevents posting, it would be helpful if the process could return a non-zero exit code.
When sendmail pipes to the list through /etc/aliases, if there is a permission problem (like on digest.mbox) the message just disappears without a trace - no post to the list, no bounce to the poster, no archive, nothing except the exception in /var/log/mailman/error and a 'SHUNTING' message. (I have some sysadmin scripts that manage permissions, and there was a bug.)
If a pipe process exits with a positive integer exit code in case of error, sendmail bounces with "554 Service Unavailable" and provides useful logging info. This would be a lot more informative than having the mail vanish into thin air.
Thanks!
Mark