Mail Server in front of Exchange Server - Dual Mail Servers?

Posted on 2004-11-02
Last Modified: 2006-11-17
we are going to physically move to a new building. I am running Exchange v6, build 6249.  There will be a change of ip addresses for my t1, but i want to catch all the mail.  My idea was to basically setup a mail server as a repository that catches all the mail on my old ip address on old t1, then sends it to my Exchange server that is sitting on my new t1 and new ip address in a totally different building.  Is there a better solution? What would be a good piece of mail server software for this repository..either linux or win based ?  How would i configure the Exchange server for this? FYi, i am using Brightmail on the exchange server.. in case this makes a difference.

Question by:renet123
    LVL 104

    Expert Comment

    You could use a Windows server to do the relay.
    If you used a Windows server, install DNS server on to it as well. Then make your own DNS entries for the other IP address so that the server uses them. This will get round any problems with old IP address information.
    No changes required to Exchage, it will just accept the messages as normal.


    Author Comment

    This will not work because one day when i have to physcally turn off my server and move it to a new building. mail has to go somewhere at that time. my vision is .....Old T1 -> mail repository relay -> Exchange Server steps would be ..
    Step 1 Old T1 configured to send mail to repository.
    Step 2 Turn off exchange server and move it to the new building.
    Step 3 New t1 turn on
    Step 4 Setup exchange server at new building
    Step 5 Configure new t1 to send mail to exchange server
    Step 6 Repository relays all mail to the new t1 and exchange server
    Step 7 Turn off old t1 once everyone in the world caches up with new mx record, and turn off mail repository

    is this a good plan? what software would i use as the relay/repository?
    LVL 104

    Expert Comment

    I did this recently.

    It was well planned.
    The domain name was spun out to a dedicated domain name registrar who had nothing to do with the hosting or the internet connection.
    With a week to go, I got them to cut the TTL down to the minimum time allowed (15 minutes IIRC).
    Then on the Friday night I changed the DNS of the A record. I didn't change the MX.


    A: :
    MX: 5

    A: : 456.456.456.456
    MX: 5

    As a further backup, I got a dynamic DNS account from and added that as a second MX record. Dyndns have a very short update time. The week before it was delivering to the old server, then I switch it to the new server.
    Saturday morning I flicked everything across, and the email that had been queued elsewhere all came in, good as gold.
    No relay server
    No email lost
    No interuption to business
    Users didn't know anything had changed.


    Author Comment

    That sounds awesome. i am going to take this into consideration. i do want to make the safety net.  Do you think Sendmail will offer some solution to the repository i spoke about?

    LVL 104

    Accepted Solution

    I have never used sendmail so cannot comment on whether it can do it or not. I have only ever used a Windows 200x machine for relaying.



    Author Comment

    This link should do exactly what i want.

    The article explains why he sets this up this way, and is closest to my needs:
    This is a quote from the link of why...the first and last reasons are my reasons too!

    -we already have an Exchange server and will not be getting rid of it
    -we don't want to spend $$ on spam software (most of what I've seen for $$ hasn't been too impressive, anyway. This multi-component system is equal to or beats out most commercial anti-spam software packages I've seen!)
    -to protect our Exchange server (a "buffer" between the bad guys and our internal mail system - no inbound connections to Exchange from the Internet. This protects, for instance, against such things as smtp auth attacks, such as described here )
    -to spread the CPU load (spamfilter does the spam scanning, Exchange the AV and delivery)
    -to be able to take the Exchange server down and Internet emails will still come in and be stored, waiting, on the spamfilter, until the mail server is back online****

    Author Comment

    i really do appreciate the help. i have learned something, so enjoy the points.

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