[Dovecot] Maximum number of connections from user+IP exceeded

[Stan Hoeppner]

On 8/19/2013 7:03 AM, Reindl Harald wrote:
> 
> 
> Am 19.08.2013 14:00, schrieb LuKreme:
>> All of a sudden I am getting these errors on one of my accounts:
>>
>> imap-login: Info: Maximum number of connections from user+IP exceeded (mail_max_userip_connections=10)
>> It was working fine last night when I went to bed, and is posting these errors nearly constantly
> 
> in case of IMAP 10 is *way* too low!
> 
> keep in mind that
> 
> * a IMAP client opens one connection *per folder*

What do you mean by "per folder"?  I've been limiting Tbird to 2 IMAP
connections for many years and, unsurprisingly, it never opens more than
two IMAP connections to Dovecot no matter how many folders I access,
tabs I have open, or searches I perform, etc:

tcp 0 0 192.168.100.9:143 192.168.100.53:1663 ESTABLISHED 13189/imap
tcp 0 0 192.168.100.9:143 192.168.100.53:1672 ESTABLISHED 13192/imap

And with the default TB limit of 5 it never opens more than 5.  Which
clients exhibit this "per folder" connection behavior?  That seems
totally unnecessary.

> * if you have 5 folders and a user with 3 devices (workstation, phone, tablet) you are done

Again, not folder dependent but client configuration dependent.  If your
client is RC it never opens more than one connection per user, and
closes the connection after each operation.

> * if you have a few imap-users behind the same NAT you are done

This isn't correct either.  It's user+IP.  So you could have 30
connections from 3 users, 100 from 10 users, through one NAT IP, with a
setting of 10.

-- 
Stan