Re: [exim] 421 too many concurrent sessions

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Author: Chris Siebenmann
Date:  
To: The Doctor
CC: exim-users, cks
Subject: Re: [exim] 421 too many concurrent sessions
> I cannot find the culprit doing this.
>
> Using Exim 4.88 on FreeBSD 11 I placed this into my configuration:

[...]
> smtp_accept_max = 10


Well, you have a limit of 10 simultaneous SMTP connections period.
Once you have ten active ones, any further connections will get this
message.

> smtp_accept_max_per_host = 5


... and a single IP can only have five connections at once.

Note that despite the names being very similar to each other,
'smtp_accept_max_per_connection' means something completely
different than 'smtp_accept_max_per_host'. One is about limits
on SMTP connections, one is about limits on MAIL commands within
a single connection.

If your problem is that you cannot see where the connections
are coming from, look at what 'exiwhat' reports, as well as
ps, netstat, lsof, and other similar tools for looking at
network connections.

    - cks