Verizon email problems

[Chris Brenton]

On Tue, 2003-11-11 at 20:00, Bruce Dawson wrote:
>
> Correct. Just to clarify and reiterate: not all SMTP receivers require
> their partner to have a reverse lookup.

This is becoming pretty common however. For example the last time I
posted to Bugtraq I received a bit over 67,000 different mail systems
validating my PTR. That's well over half the domains subscribed to the
list.

> I believe sendmail does not make
> this requirement in the default configuration. 

Depends on the flavor. Red Hat does this out of the box (as well as
Ident which is kind of useless). If you build from source I believe its
off by default, but I would have to check.

> I commented out the 'accept_unresolvable_domains' feature on CodeMeta's
> mail server so that we wouldn't receive so much spam. (Which cut down
> the spam load by about 50%). Note that CodeMeta's mail server isn't the
> same one used by the GNHLUG mailing lists.

Another little "trick" is to validate that the listed authoritative name
server are in fact giving back authoritative answers. Seems spammers
like to park on your DNS if you have not disabled recursion. 

HTH,
C