Re: [vps-mail] Issue re sendmail/ abuse (attempted relay????)

[Scott Wiersdorf <scottw@xxxxxxxxxxxx>]

On Thu, Aug 21, 2003 at 03:24:32PM -0700, Abigail Marshall wrote:
> Is there anything else I can do? I'm wondering how this sort
> of stuff impacts overall server load and performance of
> Sendmail.

Abigail,

Doing some simple testing I was able to get an average of 6 rejections
per second on a regular VPS B. It peaked at around 10, but network
connections will vary, of course (these tests were running on the same
physical box, so network connection did not interfere; my tests will
therefore reflect closely actual sendmail capacities). The maximum
load for this VPS peaked at around 1, which is what you would expect.

The test server, on the other hand, which was sending the mail (and
which I was blacklisting in my access.db file) had hit a load of 5 and
was climbing steadily before I aborted the test.

I conclude that it is far more costly to send rejected messages than
to block them; my advice to you is that if your server seems to be
doing fine, let sendmail continue as it is. It's doing a good job.

FYI, when you put a REJECT in your access.db, the connection is
IMMEDIATELY rejected when the remote host connects (i.e., sendmail
devotes no more resources beyond a socket connection once you've
connected from the remote host). This makes access.db very efficient
and nothing short of a tcpwrapper (unless you're running sendmail as
a daemon, which will be even more efficient) or an IP filter will be
more effective.

Scott
-- 
Scott Wiersdorf
scottw@xxxxxxxxxxxx
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