PureMessage for UNIX: How to increase the speed of DNS lookups

  • Article ID: 36620
  • Updated: 02 Sep 2011

PureMessage performance is strongly correlated with the performance of the DNS server, when the Anti-Spam filter is configured to perform DNS lookups (recommended).

What to do

PureMessage performs a variety of DNS checks, including reverse DNS lookups and queries that are handled via the Sophos SXL architecture. For optimal performance, install a local caching DNS server.

Although it is possible to disable network checks completely by setting the local_tests_only option in /opt/pmx/etc/spam.conf to "on", this is not recommended because it will negatively affect catch rates. You can specify the server(s) used for DNS based checks in /opt/pmx/etc/spam.d/net.conf. The net.conf configuration file also allows you set values such as "retry" and "timeout".

If you need more information or guidance, then please contact technical support.

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