Dovecot behind Load Balancer

Paolo Daniele paolo.daniele at
Wed Jul 10 12:46:32 EEST 2019

Il 10/07/19 11:44, Jean-Daniel Dupas ha scritto:
>> Le 10 juil. 2019 à 10:24, Paolo Daniele via dovecot <dovecot at> a écrit :
>> Il 10/07/19 10:20, Aki Tuomi ha scritto:
>>>> On 12/06/2019 20:02 Paolo Daniele via dovecot <dovecot at> wrote:
>>>>   Hi,
>>>>   i've a question for you.
>>>>   I've two dovecot imap/pop server behind a zen load balancer.
>>>>   Load balancing is made by lx4nat so the public ip address of my load balancer contact directly the dovecot servers.
>>>>   Since few months i've a message from thunderbird that i've reached the imap limit login for ip.
>>>>   I've triend to increase the max user ip parameter but sometimes i've the same problem.
>>>>   It's a strange things that actually i'm able to mitigate by reduce the number of cached connections in Thunderbird but it's not normal.
>>>>   What do you think about that?
>>>>   Maybe there's some tuning that you can suggest.
>>>>   Thank you,
>>>>   Paolo
>>> Have you ensured, by checking logs, that the connections are seen by dovecot to come from public IP addresses?
>>> Also, thunderbird is known to open lots of concurrent connections.
>>> Aki
>> Yes,
>> connections are coming from the ip address of load balancer (also checked with a netstat -an)
> If connection are seen as coming from the IP address of the load balancer, isn't it normal that dovecot complains ?
> That means that dovecot sees all connections as coming from a single client, which would explain why you reach that limit.
Yeah of course, but i've checked that i haven't reach the 
max_user_per_ip limit by counting dovecot process coming from that ip 
So the strange and the reason why i'm writing to you :)

Paolo Daniele                     E-mail: paolo.daniele at
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