Sendmail/Exim and IP-Address

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Author: Roderick Ford
Date:  
Subject: Sendmail/Exim and IP-Address
Gilbert T. Gutierrez, Jr. wrote:

> The lookup name does not matter on the IP address as long as there is
> one. I would point the MX record to
> "cpe-24-221-41-162.az.sprintbbd.net" not a CNAME record.
>
> For Example:
> ecloud.org NS ns1.hn.org
> ecloud.org NS aux1.hn.org
> www.ecloud.org CNAME ecloud.org
> ecloud.org MX cpe-24-221-41-162.az.sprintbbd.net 10
> ecloud.org A 24.221.41.162
>
> Many mail servers will not accept mail unless it has a reverse lookup
> record associated with it. Some mail servers will not send mail to
> servers that are referenced by a CNAME (The reverse lookup must match
> the MX record statement).


cpe-blah-blah.net is the reverse dns lookup for 24.221.41.162 which is
on the router/firewall WAN side of the box. The router forwards ports
25/110 if I ask it to. So what I was asking was if mail sent to
goes directly to MX 10 linux.bogus. inside
the LAN, transparently.

By asking about aliasing that cpe- name, i was basically asking a stupid
question. mail sent to an "alias" that is not registered domainname of
course will not even reach the machine. That is one of those questions
you might ask after midnight.

A lot of people mentioned using CNAME...which is what I was asking the
question for. The sendmail tutorial on sendmail.org said that you
cannot use a CNAME, so...?? why do they say that?