In Exchange Server 2003, Recipient Policies are used to tell Exchange which domains to accept inbound email for, and also to generate email addresses for users. An LDAP filter is used to filter users to generate email addresses for.
In Exchange Server 2007, this functionality is separated into the follwoing:
a) <b>Accepted Domains</b>: These tell Exchange which domains to accept email for
b) <b>Email Address Policies</b>: These tell Exchange to generate email addresses
Accepted Domains can be of three types:
1) <b>Authoritative</b>: Exchange is authoritative for this domain (will generate NDRs if recipients not found/resolved), and has or knows where the recipients are
2) <b>Internal Relay</b>: This is for address space sharing scenarios. Exchange may or may not have recipients, and shares the address space with other (typically non-Exchange) mail systems. Recipients not found locally are delivered to the other mail system using a Send Connector.
3) <b>External Relay</b>: Exchange acts as a relay. It does not have any recipients for this domain – it simply accepts inbound mail and forwards it to a particular external mail system.
Depending on what you want to do with email for these domains, you can create Accepted Domains of the appropriate type.
When upgrading/migrating from Exchange Server 2000/2003 to Exchange Server 2007, you need to upgrade the Recipient Policy/Email Address Policy.
Address List and EAP filter upgrades with Exchange Server 2007
Managing Accepted Domains