Re: [Asrg] What are the IPs that sends mail for a domain?

Ian Eiloart <> Wed, 17 June 2009 10:45 UTC

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Subject: Re: [Asrg] What are the IPs that sends mail for a domain?
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--On 16 June 2009 17:24:03 -0700 Douglas Otis <> wrote:

> The CSV effort proved most providers do not want their MTAs identified as
> belonging to them, even when it could improve email acceptance.  This
> might be especially true now after their support staff has been reduced.

It'll probably depend on how much difference it makes to email acceptance. 
The harder it is to deliver email without some assurance that the sender 
isn't spoofed, the better.

> Reverse DNS is already causing a large amount of resources to be wasted
> by the shabby state of the reverse name space.  Incorrectly configured
> RFC 2317 delegation, and many non-functional servers are causing MTAs to
> rapidly become resource limited when making reverse checks.   In
> addition, when your customers conduct business with Asia, they may not be
> happy to find email is being lost as a result of geographic differences
> of opinion about the role that reverse DNS might play with email.
> IMHO, all outbound MTAs should be required to return CVS records for
> their EHLO name and offer MX records for their inbound.  A mandate that
> required MX (inbound) or CVS (outbound) records would greatly help in
> identifying non-abusive email sources against a backdrop of hundreds of
> millions of bot-net controlled drones spewing email.  Systems may soon
> use ACLs as a means to white-list safe MTAs.  Perhaps the world is a few
> years from having to go to that extreme.

It's not a binary thing, though.

> -Doug

Ian Eiloart
IT Services, University of Sussex
01273-873148 x3148
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