On Wed, Apr 23, 2008 at 11:18:34AM -0400, Morris, Roy wrote:
quoted text
> I know this is not exactly a OpenBSD question but I am wondering if anyone
> can give me a sense of the performance/limitations of sendmail? Basically
> I have a machine that sends out 20,000 mails a day and once and a while
> the application sending emails for delivery complains that it has to
> wait for sendmail. I go and check the sendmail machine and it's hardly
> even breathing hard. Almost no cpu usage, memory fine blah blah ..
> 
> I am not convinced this is a problem with sendmail, just looking for
> some feedback from anyone doing volume email on openbsd.

Many MTA performance problems of this nature are not the related to
the MTA per se, but to DNS.  So much so, that it's become nearly a
SOP to thoroughly check DNS function and performance before looking
at the MTA.

That may or may not be your problem, but it's certainly a good place
to start looking.  Should it turn out to be the case, one simple
mitigating strategy is to enable BIND on the sendmail machine
(in recursive, caching mode but answering local queries only) and
set the resolver on it to use that instance of BIND.  If you're
sending to the domains on a regular basis, the cache will become
and remain populated with most of the DNS information required,
which should boost query response.

---Rsk