[Mimedefang] Macro Built-In Defaults / _ Macro Question

David F. Skoll dfs at roaringpenguin.com
Thu Jul 16 16:57:05 EDT 2009

Kevin A. McGrail wrote:

> I'm looking at the built-in Macros and the _ macro in the SendmailMacros 
> hash looks like a possibility to replace doing a reverse lookup on 
> hosts. The theory being (and someone else has mentioned this) that this 
> portion of my reverse DNS check in the milter is duplicative of a 
> reverse PTR lookup.

But you are already given the result of Sendmail's reverse-lookup in the
$hostname argument to filter_relay and friends, and it's in the
$RelayHostname global variable after filter_begin.

But even if you make a duplicate DNS lookup, it should be fast because
the answer is cached (you ARE running a caching DNS server, right? :-))



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