Reverse Dns Question...is it really necessary or not?
Jason Gurtz
jason at tommyk.com
Wed Jul 14 20:41:10 UTC 2004
Just to set the record straight, AOL does not outright block email (as
some others do) from MXs with no PTR record. They do, however, count it
as a strike against the MX. Additionally, they will not grant whitelist
status unless your MX has a PTR. In AOL's case the PTR record need not
perfectly match the corresponding A record, it's enough just that one
exist for that IP.
This means that most will be ok using just the generic PTR records as
assigned by their upstream ISP. I found that even our highly
bureaucratic ISP (SBC Inc.) was willing to assign generic PTR addresses
for our net blocks (it did take a little pushing).
More info can be found at <http://postmaster.aol.com/>
It's a fact that postmasters applying stricter policies then AOL WRT PTR
records are blocking mail from a great number of small businesses as
well as legitimate mail from third world countries with recalcitrant
ISPs. This is their right.
Having a reverse record mostly means that a receiving MX can find a
responsible domain for the sending MX's IP addy without resorting to
whois. Like other people have said, this will only be more prevalent as
time goes on.
Cheers,
~Jason
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