What would the setup look like if my network looks like this: - Exchange server - FireWall / Internal - FireWall / External (imaginary IP..) - mail.myisp.com (SMTP)

I can now successfully send mails through this setup by using an SMTP connector. This works both on the local domain and to outside addresses.

The problem is recieving mail!
What would I have to do to make that happen?
What kind of DNS records would I have to make to fit this setup?
The network only has one external address.


At least, you need a MX record pointing to the public IP address of your Exchange server and routing incomming SMTP connections to the Exchange server. Since you have only one external IP you 'll certainly would NAT incoming SMTP connections to the internal IP of the Exchange server.

Hope this helps.

  • Could I mix this with perhaps an A record? And yes, NAT would be the option. It certainly gave me a good pointer - thanks! – xstnc Nov 16 '10 at 10:27
  • So no MX records pointing to the LAN-ip of the Exchange server should be added? Just adding inbound MX to the EXTERNAL IP should do the trick? – xstnc Nov 16 '10 at 10:34
  • Would the ISP have to add an MX record too? – xstnc Nov 16 '10 at 12:42
  • if you're willing to receive mail for mydomain.com then there must be an MX record in the zone mydomain.com pointing to the external IP of your mail server. Also you may need to add a host record and his respected Reverse pointer in the zone referencing the exchange server hostname with the external IP. – Maxwell Nov 18 '10 at 9:06

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