OT: Seeking opinion about reverse-DNS lookups on SMTP HELO
Scot L. Harris
webid at cfl.rr.com
Tue Dec 14 15:22:04 UTC 2004
On Tue, 2004-12-14 at 07:02, HaJo Schatz wrote:
> To combat spam I have enabled reverse-DNS lookups of incoming SMTP
> connections. If the FQDN does not match the HELO-Identity, I reject the
> connection with a 550 Error.
>
> I have now found that this breaks communication even with reputable
> (well, an international bank that is) peers. Dunno how much more mail I
> may have lost through this... How are you out there handling that, are
> you doing reverse-lookups?
The best tool for combating spam that I have found so far is a
combination of greylisting and spamassassin. Greylisting will block 95
to 98% of spam from ever getting on your sysstem. Spamsassassin catches
most of the rest.
If you are using sendmail I have used the milter-greylist package to
provide greylisting. There are many others as well as versions for
other MTAs.
Highly recommended.
--
Scot L. Harris
webid at cfl.rr.com
I have found little that is good about human beings. In my experience
most of them are trash.
-- Sigmund Freud
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