Dear all,

I have recently migrated from my old Debian 8 (jessie) system to a new VM with fresh Debian 10 (buster) installation.

Previous dovecot version was 2.2.13 and now I have 2.3.4.1.

Dovecot was setup from Debian packages.

Mostly, it is working, but one problem is just frustrating me.

The number of some pop3-login processes are getting higher and higher until they reach my login_max_processes_count option which is equal 1000.

From ps aux it looks like this:

 

dovecot  55067  0.0  0.0   8192  6340 ?        S    00:09   0:00 dovecot/pop3-login [1 pre-login]
dovecot  55344  0.0  0.0   8192  6388 ?        S    00:35   0:00 dovecot/pop3-login [1 pre-login]
dovecot  55351  0.0  0.0   8192  6268 ?        S    00:35   0:00 dovecot/pop3-login [1 pre-login]
dovecot  55354  0.0  0.0   8192  6388 ?        S    00:35   0:00 dovecot/pop3-login [1 pre-login]
dovecot  55594  0.0  0.0   8192  6280 ?        S    00:36   0:00 dovecot/pop3-login [1 pre-login]
dovecot  56822  0.0  0.0   8192  6300 ?        S    00:36   0:00 dovecot/pop3-login [1 pre-login]
dovecot  56996  0.0  0.0   8192  6268 ?        S    00:36   0:00 dovecot/pop3-login [1 pre-login]
…

 

Once it reaches the login_max_processes_count value my users start to complain to no new mail is arriving.

Restart resolves the problem just for some time, until it will come to a limit next time (sometimes it take 1 day, sometimes 1 hour).

In my old system I had nothing like that, but I guess it could be done something wrong during migration.

I don’t know if it is significant but instead of real users I deal with only one third-party application which utilizeses 5 simultaneous tcp connections to check mailboxes via SSL\TLS.

My dovecot is not public, and there is nothing else besides these 5 connections.

Currently, in a config I have this:

 

 

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Regards,

Greg Semenov