We tried to update our Dovecot Director-Ring to 2.3 (latest version) and had one problem/bug. When we try to deliver an email from Exim to a receiving Dovecot (2.3 latest) via the LMTP-Proxy the LMTP process stays open forever and never closes. So after a few hours, we hit the LMPT-Process limit.

The problem only exists if the receiving Dovecot reports "Quota exceeded (mailbox for user is full)" back to the Exim. If this is the case the state on the LMPT process stays at "lmtp: [_IP_ RCPT TO] (lmtp) and never closes. The TCP-Connection to the Exim is then in CLOSE_WAIT state on the Proxy. On the receiving Dovecot we set the "lmtp_rcpt_check_quota=yes" option. For me, it sounds similar to this bug: https://dovecot.org/list/dovecot/2018-January/110697.html but without the SEGFAULT which makes it harder to debug it.

May you guys know why it doesn't change the state to IDLE or READY after reporting the quota issue or see something fishy in the commit above. If not I try to get a trace of the hanging process.

Greetings Pascal