> Relay under heavy network load - really many what to connect it.
> And I start to get
> "421 Too many concurrent SMTP connections; please try again later"
> in logs.
> But I don`t use rate limiting. What else can make this? And how can I
change it?
On which server and from which direction. Is that on "=>" log-line or is
your server denying connections? Because it affect which server you need to
tweak.
More to read, exim documentation 14.10 "resource control".
http://www.exim.org/exim-html-current/doc/html/spec_html/ch14.html#SECID105
Mostly you should be interested in options:
smtp_accept_max simultaneous incoming connections
smtp_accept_max_per_host connections from one host
