When will MailScanner + postfix actually say "421 too much load"

Leland J. Steinke steinkel at pa.net
Thu Feb 21 14:17:58 GMT 2008

Ronny T. Lampert wrote:
> Will MailScanner actually affect postfix's decision to go 421?
> Did anybody have this kind of situation yet?
MailScanner does not exert backpressure on postfix automatically.  We 
created a policy service that queries the size of the hold queue and 
defers messages when the queue is too big.

To reduce load on the server, the service checks the hold queue only 
once at startup.  Then it gives the same answer until spawn(8) is done 
with it.

This has worked reasonably well for us in diverting traffic from 
overloaded servers to others.


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