imapsieve: mailbox Trash: FLAG event

[Peter Schiffer]

Hi all,

after upgrade from Dovecot 2.2 to 2.3 I started to see that emails from
Trash folder are automatically deleted after ~7 days. Email clients are
not configured to automatically expunge or empty trash on log out (I
see this behavior for multiple mailboxes, with different clients).

With mail_debug enabled, I see this log message for every email that
gets deleted from Trash:

May 29 08:02:17 hostname dovecot: imap(some at mail)<7725><xxb6+VFtL+JT0CE
8>: Debug: imapsieve: mailbox Trash: FLAG event (changed flags:
\Deleted)

I have Dovecot 2.3.1 (8e2f634) and Pigeonhole 0.5.1 for sieve. My
configuration can be found here:
https://github.com/pschiffe/mailcow-dockerized/tree/master/data/conf/dovecot

There is enabled support for sieve config in sql, but all sieve tables
are empty, and there are no sieve filters for Trash flagging.

Do you know how to find the source of that Trash flag event? I need to
disable it or to configure it so it deletes emails at least couple of
months old.

Thanks all,

peter