Reverse DNS and mail

Len Conrad LConrad at
Fri Jan 9 13:25:34 UTC 2004

> > There is no requirements that the mailserver has several FQDN, it's
> > better to have each domain have an MX record to
> > the "one-and-only" real mailserver
>Yes, but our mail server could appear as or

"appear" where, specifically?

PTR?  HELO hostname?  SMTP greeting?   MAIL FROM:?

>, depending on
>who is sending email (we host both and

>So wouldn't a
>recipient mail client want's IP address to resolve to and
>'s IP address to resolve to

Repeating from my earler msg in this thread:

"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)."

>   Conversely, wouldn't an email
>client that does reverse DNS reject email where's IP address
>resolves as


>Another way to ask this is that if and have the same IP, how
>does one guarantee that upon reverse DNS lookup that joe at's IP
>address resolve to  Maybe DNS will return

it doesn't matter.

I suggest that you implement my DNS/SMTP advice and report back if you have 
problems delivering mail.


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