Mailserver requirements

Mon Apr 5 21:30:36 UTC 2004

Hi Arnold-
Whether or not you will accept mail from an address without a (matching?)
reverse record is usually an option on your mailserver software. 
In terms of outbound mail, AOL, for example will no longer accept mail
unless the reverse is present.
Some providers insist that it match, which makes things a little dicey if
your mail server is handling multiple domains. I've gotten around that by
wasting an ip address for each domain, and setting up the reverse records
accordingly. Also, lots of folks are now verifying the validity of the
sender to try to prevent spoofing the mailfrom. (although the spammers only
have to spoof a valid email address to get around that)

-Keith

-----Original Message-----
From: owner-nanog at merit.edu [mailto:owner-nanog at merit.edu]
Sent: Monday, April 05, 2004 5:03 PM
To: NANOG
Subject: Mailserver requirements

Today I run across a MTA which refused to accept mail because it could
not detect an MX record for the reverse mapping of the IP address of the
server which tried to deliver mail. Is this correct?

Or: if A is the IP Address of server trying to deliver mail, does
mx(reverse(A)) have to exist?

-- Arnold