John Rudd wrote:
Stuart Johnston wrote:
Peter H. Lemieux wrote:
Billy Huddleston wrote:
Reverse DNS is a must. I'm surprised at how many people still haven't
got that yet in the IT world.. (Consultants mostly..)
It's not uncommon outside the industrialized world. Last few days I got
a few false positives for a client that was corresponding with folks in
the Caribbean.
One of the few services I believe AOL provided the rest of us was
deciding a few years' back not to accept mail from servers without
reverse DNS. Suddenly lots of admins had to deal with the problem of
correct server configuration because you couldn't fail to deliver
mail to the millions of AOL users worldwide.
Unfortunately, AOL only validates in one direction and some people
only do the bare minimum.
So, they only look to see that the IP address has a PTR record, but
don't verify that the PTR record's hostname resolves back to the IP
address?
That's correct. You can test it here:
http://postmaster.aol.com/tools/rdns.html
You can put in for example: 209.74.97.115 whose rdns resolves back to a different IP. AOL
specifically says:
If the sender's domain is the only domain sending mail from a specific IP address, we recommend that
the reverse DNS entry (PTR Record) match the domain name (A Record), but we do not require it.
