Postfix, dovecot, cron and empty envelope from

szatox · Advocate Joined: 27 Aug 2013 Posts: 3171

Somewhere in December my pigeonhole sieves inside dovecot stopped properly handling cron's reports. I finally tried to figure out what's going on, and it turns out my sieves don't match sender address anymore because those email no longer have envelope from address.
Note: envelope from is not necessarily the same as the sender in the message. The latter is properly defined as "Cron.. yada yada" <root@machine>. Like in: the second part works.

Although I don't know which update broke the whole thing, after a few tests I'm fairly confident that postfix is the culprit here.
So, how do I force postfix it to set envelope from when forwarding mail from daemons, without overriding envelope from on mail incoming from the internet? I just need a pointer in the right direction; should be able to figure out the details once I know what to look for...

acmondor · Posted: Sun Jan 14, 2024 3:54 pm Post subject:

Might you be using mail-mta/ssmtp?

I had a similar issue quite a while back and if memory serves me correctly it was due to a change in ssmtp. Specifically, the FromLineOverride setting in /etc/ssmtp.conf. It was no longer defaulting to YES, so I had to uncomment the following line:

#FromLineOverride=YES

Hope this helps.

szatox · Advocate Joined: 27 Aug 2013 Posts: 3171

No, I use postfix. And I see ssmtp actually conflicts with postifx.
Also, mail delivery to dovecot goes via unix socket using lmtp, and emails from other sources do have envelope from set, so it's not like I my toys suddenly started to strip it.
Finally, I called on the power of git to find out if there were any changes to /etc recently, but found nothing even remotely relevant.

acmondor · Posted: Sun Jan 14, 2024 5:12 pm Post subject:

Ok, sorry, I use postfix and dovecot as well, but only on my main mail server and other machines use ssmtp to get email over to it. Email from cron jobs on the mail server itself never had such an issue. My cron jobs are run by sys-process/cronie and that uses /usr/sbin/sendmail provided by postfix for sending email.

nicop · n00b Joined: 10 Apr 2014 Posts: 46

This is the mechanism that has been hardcoded since 1.7.0 :
https://github.com/cronie-crond/cronie/commit/d5d7db6a42f8c3ae6f6bd1efc767ae3fe97f4734

We have to wait for the next version :

szatox · Advocate Joined: 27 Aug 2013 Posts: 3171

Huh.... That's interesting.

From https://github.com/cronie-crond/cronie/pull/118

sam_ · Developer Joined: 14 Aug 2020 Posts: 1697

See bug 922477.

szatox · Advocate Joined: 27 Aug 2013 Posts: 3171

Thanks.
Alright, so, I updated cronie to 1.7.1-r1 and the problem with daemon explicitly setting an empty return-path is gone.
Still, on cronie's github it says that it will be set empty unless MAILFROM is explicitly set (it is not set on my system).

So, with the newest cronie in portage emails are sent correctly on my systems, even though according to upstream they shouldn't. Is current behavior permanently patched by gentoo devs, or did the authors completely back out of the idea of changing default behavior, or should I expect it to break again with the next version bump?

sam_ · Developer Joined: 14 Aug 2020 Posts: 1697

They reverted the change upstream after some discussion and we backported it. Are you sure you're looking at the latest GitHub issue? The one filed by Hanno in the bug I linked is clear I think.

szatox · Advocate Joined: 27 Aug 2013 Posts: 3171

Ah, I think I understand it now. Basically, the default behavior was reverted, so it no longer breaks old installations, but it can easily be changed server-wide via env, so there is no need to modify crontabs for all users.
This is probably the best result possible. Kudos to Hanno for getting this sorted with upstream.