mail is handled by

mfoley · 09-29-2022, 10:13 PM

I have a mail server at 1.2.3.4, FDQN: mail.obfuscate.com. It hosts several domains for web and email, for example hosted1.org. I'm trying to sort out what is correct for SPF and rDNS, etc. so recipient servers don't hate me. Given the above, would these be correct headers:

Code:

From maillist@hosted1.org  Thu Sep 29 00:58:49 2022
Return-Path: <maillist@hosted1.org>
Received: from mail.obfuscate.com (rrcs-1-2-3-4.mail.obfuscate.com [1.2.3.4]
:
Mark Foley <mfoley@hosted1.org>

or rather these:

Code:

From maillist@obfuscate.com  Thu Sep 29 00:58:49 2022
Return-Path: <maillist@obfuscate.org>
Received: from mail.obfuscate.com (rrcs-1-2-3-4.mail.obfuscate.com [1.2.3.4]
:
Mark Foley <mfoley@hosted1.org>

The difference being in the 'From ' and 'Return-Path:' headers. As I understand it, these must match. Since the IP for both hosts is 1.2.3.4, the rDNS can only refer back to one of them 'Received:' so, my MX record for hosted.org needs to be mail.obfuscate.com, right?

scasey · 09-30-2022, 04:02 PM

Both appear to be correct to me. Two different senders using the same email server.
The Received header is written by the receiving MTA, as I understand it, and will reflect information about the server that connected to it to deliver the email.

I, too, host several domains with only one MTA. Yes, the MX record for each domain will specify the actual mail server (mail.obfuscate.com in your case)
I also have an A record for each hosted domain (mail.otherdomain.com) that specifies the IP address of the real mail server. Used by users to login to the mail server. They need not, and typically don’t, know the name of the real mail server.