Any way to limit number of active IMAP/POP3 sessions from a single user / per user?

[Alexey Asemov (Alex/AT)]

I can confirm setting mail_max_userip_connections from database in 
userdb query *does not* work at all. User can still open multiple 
connection above the limit, seems like it has no effect. I thoroughly 
checked DB response and it contains proper field name/value.

I am using dovecot 2.2.31.

Also, I have mail_max_userip_connections set globally in the dovecot 
configuration file and wonder if this can interfere, but at least some 
other settings do not and so I doubt it's the cause.

So for now I have to go with writing a policy server for that it seems :)

I assume it does not work because user/IP limit is probably checked 
before parsing DB parameters.
Maybe dovecot code can be adjusted somehow so it allows setting 
mail_max_userip_connections from userdb before it's processed?