Query regarding MX records


I have a query regarding a server recieving mail.

Let's say I have serverA, serverA.kam.com. I have an application that can receive email on application@serverA.kam.com

If I send mail from my Outlook which connects to Exchange on the same network, will the mail be received by the server?

Or do I need a specific MX record pointing serverA.kam.com to serverA.kam.com?

It's confusing me a little!
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tismetooConnect With a Mentor Commented:
Hi Kam

This is up to the developers of the mail system that is responsible for delivering mail to the recipients domain. If you use a mail proxy it would be the responsibility of their provider, otherwise it is the writer of your mail system.

The DNS guys just respond to queries - not their responsibility to determine what records people decide to use or not.
Your exchange server needs to be able to resolve where to send mail for the domain servera.kam.com. The potential issues are if your exchange server is authoritative for the domain servera.kam.com or kam.com, or if servera.kam.com is not a domain on the exchange server then it needs to be able to resolve a DNS MX record for that domain.

If they are both internal, then put a primary DNS domain on your local DNS server and add an A record and MX record for servera, but this won't work for the outside world.
kam_ukAuthor Commented:
Hi there

Thanks for the reply.

I had a read of RFC 2821, and it has the following statement;

"If no MX records are found, but an A Record is found, the A Record is treated as
   if it was associated with an implicit MX Record, with a preference of 0,
   pointing to that host."

Does this mean that if there is no MX record for serverA.kam.com, its A record will be used instead as an 'implicit' MX record?
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I have never experienced that working. It may be in the RFC,  but you are dealing with manufacturers that may or may not have implemented all the criteria in their software - usually they haven't because not all recommendations are a good idea. In this case if someone hasn't got an MX record maybe they don't want mail to that domain and implementing the clause you mention just puts more traffic on the internet - just one interpretation that may be taken in this case.

Stick with an MX record, which definitely will work.
kam_ukAuthor Commented:

Ok, makes perfect sense.

Sorry - just one follow up questions - when you say, ""but you are dealing with manufacturers that may or may not have implemented all the criteria in their software ", do you mean the manufacturers of the software that is sending the mail, or manufacturers of the DNS system?

Let's say - for the sake of argument - that the RFC -had- to be followed and lack of an MX mean the A record should be used. Is it up to the programmers of the software that wants to send the mail that need to add this functionality, or up to the developers of whatever mail system that email passes through, or up to the developers of whichever DNS system is used?
kam_ukAuthor Commented:
Thanks...excellently answered, many thanks!
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