Reverse DNS and mail
LConrad at Go2France.com
Wed Jan 7 19:01:40 UTC 2004
>I am thinking about (finally) setting up reverse DNS. Occassionally someone
>reports the error " (reason: 501 Domain must resolve)" when trying to send
>mail to us. I simply want our mail servers, which serves mail for several
>domains, to work properly with reverse DNS.
>How does one setup reverse dns when a server supports multiple (virtual)
Set up as below (Len's "best practices") and I doubt you will ever have any
trouble getting your mail delivered (and if you do, I'd like to know):
1. the IP A.B.C.D of the MTA has a PTR hostname (eg: label.domain.tld) ...
D.C.B.A.in-addr.arpa. PTR label.domain.tld.
2. ... which hostname has an A record whose rdata field matches the MTA's
IP (and preferably an MX).
label.domain.tld. A A.B.C.D.
label.domain.tld. MX 10 whatever
In the MTA's SMTP settings:
3. The MTA's HELO hostname is the same as the PTR hostname:
4. the MTA's SMTP-greeting hostname is the same as the PTR hostname:
Note that the (virtual) envelope/recipient domains of the traffic allowed
by the MTA's policies are not a consideration in the above settings (the
ESD/ERD don't have to match the above label.domain.tld).
http://MenAndMice.com/DNS-training : London; San Jose; Chicago
http://IMGate.MEIway.com : free anti-spam gateway, runs on 1000's of sites
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