by lunarg on January 18th 2010, at 13:30

When you are running an Exchange server, and have your users access the server from outside the company network, you usually have to open up access to OWA. This enables users to access their mail, contacts and appointments by using an internet browser. Occassionally, someone also has a ActiveSync enabled phone that they would like to use. This protocol also uses OWA for syncing data. And very rarely, there's also a guy (usually the CEO) who simply wants to use its Outlook to connect - this is possible through web as well using RPC-over-HTTP(S), but that's information for another blog post (on another day in the far far future...) .

One of the hassles when configuring this, is the fact that you have to provide your users with a lot of configuration parameters. While you can't really avoid the username and password, there is something you can do to allow auto-detection of the server dns name.

Creating an auto-discovery DNS record

The idea is to create a specially crafted CNAME to point to your real server DNS name. The software that support the Exchange auto-discovery will use this DNS record to detect and configure the server configurations of the client.

Note that you need to have access to your DNS configuration for your e-mail domain: if your e-mail domain is (i.e. your addresses end with, you need to be able to manage that particular domain.

Also, in the code below, I use my domain name as an example. Substitute it with your own.
When using your own (private) Exchange server

Create a CNAME record, pointing to your Exchange server.


If the second record does not resolve, you need to create it as an A record to your Exchange server, and be sure it resolves correctly to your server (adjust IIS if necessary).

As said earlier, you need to substitute the domain name with your own e-mail domain name.

When using Microsoft Online (hosted Exchange or BPOS)

Like stated above, create a CNAME, but have it pointing to the servers of Microsoft Online.


Use the following DNS names to point the CNAME to, depending on which region you are subscribed.

  • For North America:
  • For Europe, the Middle East, and Africa:
  • For Asia and Pacific:

Once again, note that you need to substitute the domain name with your own e-mail domain name.

Note that this is documented more elaborately on Microsoft Technet.

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