Correct MX setup for multiple domains hosted on the same exchange server.

Posted on 2007-10-08
Last Modified: 2008-01-09
Hi guys,

In regards to hosting multiple domains on one exchange server.

If we setup a primary domain called and setup reverse dns to

Should all other domains be setup with mx as that way reverse dns will work on all domains?
ie. domain = mx =
     domain = mx =

or should we be using an A record setup and then using that as the mx record
ie. domain = mx =
     domain = mx =

I realise both methods would work but just wondering which would be the prefered method and which would give us better luck not being filtered as a spam site
Cheers for a heads up!
Question by:mishramanuj
    LVL 39

    Accepted Solution

    Flip a coin, it matters that much.

    Will your customers care if people who can sniff DNS records know that you are hosting their mail?
    LVL 13

    Assisted Solution

    It doesn't matter what your rDNS record shows.  The rDNS record doesn't have to match the MX record.  The purpose of the rDNS record is basically just to show "ownership" of the IP and that there is some sort of record setup on it.

    Author Comment

    Haha thats how we viewed it but I was a tad unsure how spam guards sniff DNS. ie if reverse dns reports a different address to the mx record it may decide its a borked email server address
    LVL 70

    Assisted Solution

    by:Chris Dent

    Blue is right, it doesn't have to match the MX.

    The PTR Record must match up with the name the SMTP Server is sending out as.

    That is, if the server is configured to send out as, the PTR Record must match the IP the server uses to send to


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