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I'm using Russell Coker's postal software to stress-test our mail server.

But I can't squeeze more than 24576 messages per minute out of it!

This seems to be a limitation on postal's side as I can fire up another instance on another machine (or the same machine) and easily squeeze through another 24576.

[root@client test]# postal -m 32 -M 4 -t 256 -c 128 -r 0 user-list
time,messages,data(K),errors,connections,SSL connections

Any idea if there's something else I'm missing or if there's something else I can change? After source-diving, I observed the throttling code doesn't even run when the rate-limit is the default (0), so it's not that.

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24576 = 3*8192 or 24*1024. That seems fairly significant. – Hyppy May 20 '11 at 18:47
Yeah, it is a rather nice round number. – MikeyB May 20 '11 at 19:02
Have you tried running another benchmark? e.g. – Philip Reynolds May 20 '11 at 23:34
up vote 1 down vote accepted

I ended up writing a python script that would spawn a number of postal processes and aggregate the results.

Sometimes it's not worth solving the actual problem, but putting in a sensible solution that works around it.

If anyone happens to need to solve this particular problem in the future, get in touch with me and I may be able to pass the code on to you.

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Did you try to give the user running postal more than 1024 file handles?

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