# Imap proxy limited to about 210 connections

**URL:** <https://www.ruby-forum.com/t/imap-proxy-limited-to-about-210-connections/238622>\
**Category:** NGINX\
**Created:** [January 20, 2014, 11:32pm UTC](https://www.ruby-forum.com/t/imap-proxy-limited-to-about-210-connections/238622 "2014-01-20T23:32:16Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [January 20, 2014, 11:32pm UTC](https://www.ruby-forum.com/t/imap-proxy-limited-to-about-210-connections/238622/1 "2014-01-20T23:32:16Z")

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I have nginx proxying imap and pop between 3 different backend servers,  
but  
it seems to be limited to about 210 concurrent connections. Requests  
beyond  
this get a connection timed out. I tried adding more worker processes  
but  
that didn’t do anything. I have multi\_accept on and have raised the  
number  
of worker\_connections, but still no luck. I see rate limiting and  
connection bandwidth limiting, but these appear to apply to the http  
protocol and not the imap/pop protocol. What parameters to I adjust to  
increase the number of concurrent sessions to imap/pop?

Posted at Nginx Forum:

> **[imap proxy limited to about 210 connections](https://forum.nginx.org/read.php?2,246642,246642#msg-246642)**
>
> I have nginx proxying imap and pop between 3 different backend servers, but it seems to be limited to about 210 concurrent connections. Requests beyond this get a connection timed out. I tried adding more worker processes but that didn't do anything....

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**Author:** ![bidwell](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/b/e79b87/32.png) [@bidwell](https://www.ruby-forum.com/u/bidwell)\
**Post date:** [January 21, 2014, 12:40pm UTC](https://www.ruby-forum.com/t/imap-proxy-limited-to-about-210-connections/238622/2 "2014-01-21T12:40:19Z")

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Hello!

On Mon, Jan 20, 2014 at 05:31:30PM -0500, bidwell wrote:

> I have nginx proxying imap and pop between 3 different backend servers, but  
> it seems to be limited to about 210 concurrent connections. Requests beyond  
> this get a connection timed out. I tried adding more worker processes but  
> that didn’t do anything. I have multi\_accept on and have raised the number  
> of worker\_connections, but still no luck. I see rate limiting and  
> connection bandwidth limiting, but these appear to apply to the http  
> protocol and not the imap/pop protocol. What parameters to I adjust to  
> increase the number of concurrent sessions to imap/pop?

In nginx itself, tuning worker\_connections should be enough. If  
it doesn’t help, it indicate the problem is elsewhere - i.e. you  
either have to tune some system limit (try looking into error log  
to see if there is something there) or your backend servers.

–  
Maxim D.  
[http://nginx.org/](http://nginx.org/)