spf at metro
Jul 20, 2004, 11:56 AM
Post #2 of 2
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I have wondered about that question too. But what ptr does is, if your
mailserver with ip 1.2.3.4 saying to be mydomain.com connects to a receiving
server then the receiving server will look up the reverse PTR records
for 1.2.3.4.
For each PTR result (which is a hostname) that ends with mydomain.com it
does an A lookup, and if this A lookup results in 1.2.3.4 again, the
result is PASS.
Also, have a look at http://spf.pobox.com/mechanisms.html#ptr
If you have two domain names, and just one IP address that acts as an
outgoing SMTP server for those two domains, publishing 'v=spf1 a:1.2.3.4
-all' or 'v=spf1 a:1.2.3.4 ~all' for both domains suffices. Note that
for other (sub-)domains you will probably also want to specify spf
records. Eg, if there's an A record for www.mydomain.com, be sure to
specify something like 'v=spf1 -all' (if of course, you never intend to
send mail with a MAIL FROM of www.mydomain.com).
Hope this helps,
Koen
On Tue, Jul 20, 2004 at 12:49:37PM -0500, RAY JEFFREYS wrote:
> not sure i understand "ptr" question on wizard....is there help
> somewhere...
> we have two domain names that could be used for our IP address...
> the question is not clear concerning "any host whose name ends in ..."
> the answer is yes if it matches our IP number, which I think is what
> they're asking???
>
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