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MX Record and A Record setup for SBS2003 server

Posted on 2004-11-24
Medium Priority
Last Modified: 2012-06-21
Hi Folks,
I have setup a SBS2003 server and I have some confusion on the MX record
and the A record that should point to the new exchange server.
Heres the details:
SBS2003 server w/ static IP address behind a firewall that port
forwards to the new server, (single nic)  The internet works

I want my third part ISP (Verio) to forward the email to the external
ip address of the new server.  The nameserver and website should stay
at Verio:

What exactly is the procedure for this?  
This is what I have done so far:

-Set a new A record at the Verio server and called it:
xyzNet.xyz.com. IN A xx.xx.xx.xx   where xyz is the name of the
established domain and xx.xx.xx.xx is the ip address of the new
-Set the MX record:
xyz.com IN MX 10 xyzNet.xyz.com.  with the ip address to the new
Added a 2nd MX record:
xyz.com IN MX 20 xyz.com  with the ip address of the Verio server
(where it is now.)
Is this correct?  Do I need to create an A record? or just the MX
Do I need to make any changes on the SBS2003 Exchange Server?  Does  the A record in the Verio Webserver need to correspond to anything on my exchange server?
Do I need to wait for propogation through the InterNic servers before it starts working?

any help would greatly be appreciated.
Question by:dwcorwith
  • 3
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Accepted Solution

brownmetals earned 1600 total points
ID: 12668455
Hi there.

I just did the same exact thing with my SBS2003 server. I have access to the DNS records at my ISP, so I was able to modify them myself. I did the following:

1. Create an A record - smtp.domainhere.com    - Public IP address of your network
2. Create an MX record - smtp.domainhere.com  - domainhere.com
3. Set Priority - set the new MX record to have a higher priority (5 for example), and set ISP's MX to a lower priority (10 for example).
4. Open SMTP Port on Firewall - my ISP does managed firewalling for me, so I had them allow SMTP traffic (Port 25)

Now email hits my SBS2003 box first. If it's unavailable, the email will collect at the ISP because I still have their mail server setup with a lower priority.

Hope that helps.

Author Comment

ID: 12669607
Thanks for confirming.  That is essentially what I did.  Did you have to make any changes on your SBS2003 server? Or is the default setup sufficient?  Did it start working immediately? or did you have to wait for it to propogate?

Expert Comment

ID: 12669685
Hi Dave.

The only thing I did on the SBS2003 box is to make sure you have an SMTP connector setup in Exchange 2003. It does take some time to propogate, say 72 hours max, but I did this all on a Friday night, and it was up and running on Monday morning. At first, the traffic was being blocked. Then I realized I needed to open Port 25 for SMTP traffic. Once I did that, the emails came flying in.

Good luck!
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Author Comment

ID: 12670229
Ok, the exchange server is working now for outgoing traffic so I presume the SMTP connector is setup.  What is I was confused with was actually changing the A record.  I didn't know if it was possible to just change the MX record or if it needed a corresponding A record changed as well.
Thanks again.

Expert Comment

ID: 12670262
You usually need an A record to point to the MX record. Looks like you've got everything covered.

Thanks for the answer/grade - enjoy the holiday weekend.


Author Comment

ID: 12670555
I will, you do the same

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