[Dovecot] imap-login processes

[Joe Allesi]

"I tried switching to high-performance mode yesterday.. It seemed to end up
with sort of the same results, though harder to diagnose. Each process I
guess ended up hitting the login_process_size = 64 max and then stopped
responding."

We had this same problem, and switching to high-performance mode helps.
However, finding out which user or application is logging in, and
controlling the end-user is the only way to fix it. In our case it was a
multi-threaded application that used IMAP (excessively). Monitoring the
maillog should help point you in the right direction. Dozens of these per
minute should throw up a red-flag:

May 16 17:36:16 <hostname> imap-login: Login: <user> [::ffff:<IP_Address>]

Joe