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postfix-users: Re: Understanding postscreen timeouts

Re: Understanding postscreen timeouts

From: Wietse Venema <wietse_at_nospam>
Date: Thu May 01 2014 - 21:38:14 GMT
To: Postfix users <>

> I'm using postfix-2.10.3 with fedora20 and have configured postscreen with
> spamhaus, barracuda, and a few other DNSBLs. I'm however occasionally
> receiving the following timeout message:
> May 1 17:15:01 mail01 postfix/postscreen[4429]: warning: dnsblog reply
> timeout 10s for

This time limit has unfortunately escaped my attention. It is not
yet configurable.

The warning message means that postscreen gives up waiting for the
DNS lookup result. This is a safety mechanism.

> I'm also using a half-dozen RBLs, but they don't all always timeout.

I see occasional timeouts on residential and co-located servers.
By default the resolver *system library* routines wait 5s before
retrying; this may be configurable in resolv.conf, but the
postscreen time limit is still hard-coded.