After Domain Name Service (DNS) is configured and working properly, you can use policies to add SMTP addresses to your users accounts. Alternatively, you can administer any of these properties individually by accessing the user object from the Active Directory Users and Computers Microsoft Management Console (MMC) snap-in.You can define a policy that states that all users with the company name Northwind Traders have an SMTP address of email@example.com mailto:firstname.lastname@example.org. Additionally, within a company, you can identify other attributes on which to relate a rule, such as custom attributes. There is no way to force application of a policy because it is applied immediately and enforced within one hour.When you create a recipient policy, note that a default policy is in place. This default policy is modifiable.
Note Recipient policies are designed to replace the function of site addressing in Microsoft Exchange Server 5.5, with a little more flexibility. Site addressing applied proxy addressing rules to all users in a site, whereas recipient policies give more flexibility on how you group the users to whom the addressing rules apply.
In Exchange Server 5.5 or Microsoft Exchange 2000 Server mixed-mode, only the default recipient policy is in effect. The default recipient policy is created based on the site addressing of the Exchange Server 5.5 site. The default recipient policy that is based on the site addressing of the Exchange Server 5.5 site permits backward compatibility with Exchange Server 5.5. In native-mode, multiple recipient policies can be in effect on different groups of users.