[45931] in North American Network Operators' Group
Re: Reverse DNS and SMTP
daemon@ATHENA.MIT.EDU (Conrad A. Rockenhaus)
Thu Feb 28 15:49:42 2002
Message-Id: <200202282046.g1SKkOeN005632@mail4.megamailservers.com>
Date: Thu, 28 Feb 2002 20:46:21 -0000
To: Patrick Muldoon <doon@inoc.net>, nanog@merit.edu
From: "Conrad A. Rockenhaus" <conradr@skyphusion.com>
Errors-To: owner-nanog-outgoing@merit.edu
Patrick Muldoon <doon@inoc.net> said:
>
> If an ISP who doesn't have reverse DNS setup correctly on their
> mail servers, we point them to the RFC's and generally offer to help
> them correct it.
> We have noticed that our spam has reduced drastically, and the
> complaints are few, but alas this is a double edged sword, where if you
> even block 1 legitimate e-mail out of the 100K+ that we receive daily,
> someone is going to complain.
To be honest, I would do this as a last resort. For example, if their ISP's
(or their own, if they have the block delegated) DNS server is misconfigured,
etc, you might have a issue. Also, some admins have no clue what reverse dns
is, seriously :).
I would use a service like MAPS first to see if that resolves the issue, and
use this as a last resort.
If they don't have an issue with blocking unresolvable ips, then they
shouldn't have an issue with just using an rbl ;).
--conradr
