Applies to: Exchange Server 2010 SP3

Topic Last Modified: 2011-11-08

If you try to use the Autodiscover feature in Exchange Server 2007 together with offline address books (OABs) in an Active Directory forest that contains a single-label domain name, Autodiscover won’t work as expected.

Single-label DNS names are DNS names that don’t contain a suffix, such as .com, .corp, .net, or .org. For example, Contoso instead of

This issue occurs because Outlook assumes that the default e-mail address policy would map to a publicly resolvable name. To send mail over the Internet, SMTP domains in an e-mail address policy must resolve to one of the top-level domains supported by RFCs (for example, the top-level domain names described in RFC 1591 - Domain Name System Structure and Delegation). Outlook requires that the proxy addresses defined in the e-mail address policy contain at least two levels of hierarchy in the name. Specifically, the addresses must contain at least one dotted suffix that’s acceptable by Outlook. The following list includes examples of names that Outlook considers valid:

Although, Outlook considers contoso.test to be a valid domain name, it isn’t publicly resolvable according to RFC standards because there is no top-level domain called "test" on the Internet. However, such a domain name could be used to route internal e-mail only. Recipients couldn’t receive mail for that domain from outside the company.

What can I do to fix this?

To maintain your second-level domain (SLD), the proxy addresses in your default e-mail address policy must include at least two levels of hierarchy (for example,

Depending on your organization’s structure, run one or both of the following commands:

  • Mixed Exchange 2003 and Exchange 2007 organization

    • If the e-mail address policy (called a Recipient Policy in Exchange 2003) exists on an Exchange 2003 server, the policy won’t have the OPATH filtering syntax. In this case, run Command 1 followed by Command 2.

    • If the e-mail address policy exists on an Exchange 2007 server, run only Command 2.

  • Pure Exchange 2007 or Exchange 2010 organization   Run only Command 2.

Command 1

Copy Code
Set-EmailAddressPolicy "Default Policy" -IncludedRecipients AllRecipients

Command 2

Copy Code
Set-EmailAddressPolicy "Default Policy" -EnabledPrimarySMTPAddressTemplate ""

For detailed syntax and parameter information, see Set-EmailAddressPolicy.