Issue with one user only, exceeding connections

[Richard]

> Date: Wednesday, June 08, 2022 14:14:23 -0500
> From: Jeremy Schaeffer <kb9mfd at phonesplus.biz>
>
> I keep having this issue with one user, and I have to restart
> dovecot several times a day to clear it. What I have is a postfix /
> dovecot mail server (Centos 7) and about a dozen users. All
> mailboxes are imap ssl. I monitor about 4 mailboxes on my computer
> and tablet. I use Thunderbird on the computer (cache connections at
> 2) and K9 on the tablet, but one user of the four I keep getting
> "Maximum number of connections from user+IP exceeded" and I have
> the maximum at 50 "(mail_max_userip_connections=50)" so its hard
> for me to believe I am actually exceeding it unless dovecot/client
> is not dropping connections and keeps starting new ones until it
> reaches the maximum, but again, only for one user, even though I am
> monitoring 4 on the same devices. Any idea how to troubleshoot
> this? I don't know if I should be looking at dovecot or the
> clients, or what I need to look for. It's been going on since I put
> this server in use over a year ago. I also have issues with Outlook
> clients disconnecting, just outlook, is there any recommended
> settings to make Outlook work smoother?
> 
> Thanks! - Jeremy
> 
> Config -
> 
># 2.2.36 (1f10bfa63): /etc/dovecot/dovecot.conf
># OS: Linux 3.10.0-1160.11.1.el7.x86_64 x86_64 CentOS Linux release
># 7.9.2009 (Core) Hostname: ***

> }
> protocol imap {
>    mail_max_userip_connections = 50
> }
> 

On my centos-7 dovecot install (same versions you indicate you are
using), that connection-limiting line is in:

  /etc/dovecot/conf.d/20-imap.conf

while you appear to have it in the main dovecot.conf file. If you
have that in both places I'm not certain which one takes precedence,
but you might want to check. [In my setup almost all the
configuration pieces are in include files, rather than the main
.conf.]

Starting with a "ps" (and grep &etc.) it's fairly easy to see how
many connections any account has open. An open mailbox has one or two
connections and then every folder (under a mailbox) that is open will
have a connection associated with it too, which pushes up the count
quickly if someone holds a lot of folders open.