Dovecot behind Load Balancer

Paolo Daniele paolo.daniele at
Wed Jul 10 11:24:55 EEST 2019

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
connections are coming from the ip address of load balancer (also 
checked with a netstat -an)
I know that thunderbird has this problem and i haven't problem since the 
numbers of email domain increase.
I'm not sure the impact of rising the max user ip to an higher value in 
terms of ram consumption and cpu
Any suggestion?
Thanks for your answer!

Paolo Daniele                     E-mail: paolo.daniele at
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