From: L. Mark Stone (lmstonernome.com)
Date: Mon Dec 13 2004 - 08:54:52 CST

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To help settle an internal debate, I am keen to get views on the "correctness"
of A, MX and PTR records for successful mail exchange.

We use postfix to provide gateway email services to some of our clients, along
with spam cleaning. A prospective client is using a competitor for network
maintenance, and they are not happy with their service levels. We were asked
to do a network audit, and we found a number of issues (not just mail), like
servers that haven't been patched in years, no virus updates for months, etc.
(don't get me started...). But as far as their mail setup is concerned, none
of us can say conclusively that their current setup isn't quite right,
although it isn't how we would have set it up. To convince the prospect to
move their anti-spam service, as well as their network maintenance to us, we
are trying to document why their current mail setup may be incorrect, and we
would be grateful for anyone's views on this, please.

This prospective client is a company whose domain is, say, "company.com". In
public DNS space, their primary MX record points to "mail.company.com". The A
record underlying that MX record points to the mail server for a spam
cleaning service (again, not us). The associated PTR record points to the
original mail server provided to company.com by their ISP. The secondary MX
record points to the ISP's mail server, and the associated A and PTR records
match up.

As far as incoming mail is concerned, the spam cleaning service processes the
mail for the domain and then is configured to forward it to the company's
Exchange server that has a fixed public IP address, but no DNS records in
public DNS space.

As far as outgoing mail is concerned, it is all sent through the ISP's SMTP
server.

Can anyone say conclusively that:

1. This set up is not RFC compliant, or,

2. Users in this domain will have trouble sending/receiving email to some
domains (and why).

Thank you!

--
_______________________________________________________________
A Message From... L. Mark Stone

Reliable Networks of Maine, LLC

"We manage your network so you can manage your business."

477 Congress Street
Portland, ME 04101
Tel: (207) 772-5678
Web: http://www.RNoME.com

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