A. Assuming you've run DomainPrep on the domain, which grants the Exchange permissions required to maintain mail attributes of objects and creates the necessary Exchange containers and objects for the domain (i.e., Microsoft Exchange System Objects container at root of domain for mail-enabled public folders, Exchange Domains Servers and Exchange Enterprise Servers groups), the component that actually updates objects is the Recipient Update Service (RUS). RUS exists at both an enterprise level (to handle objects with an organizational scope, e.g., message stores) and per-domain level (mail and mail-enabled objects). The per-domain instance handles the updating of objects for each domain by checking for objects with a mailNickname attribute that don't have the other mail attributes populated, in a domain with no Exchange server.

For the first Exchange server in a domain, Exchange will automatically create an RUS instance for the domain on the new Exchange server. You need to manually allocate a domain with no Exchange server to an Exchange server and manually create an RUS instance. To do so, perform these steps:

  1. Start the Microsoft Management Console (MMC) Exchange System Manager (ESM) snap-in (Start, Programs, Microsoft Exchange, System Manager).
  2. Navigate to Recipients, Recipient Update Services.
  3. Right-click the right pane and select New, Recipient Update Service, as the figureshows.
  4. Click Browse and select the name of the domain that the RUS instance is for, as the figure shows. Click OK.
  5. Click Next.
  6. Select the Exchange server responsible for updating the domain by clicking the Browse button again. Remember, choose an Exchange server that's close to a domain controller (DC) for the domain. The RUS works by performing many LDAP queries, and good connectivity is vital. Click Next.
  7. You'll see a summary dialog box, as the figureshows. Click Finish.

    The first time the RUS runs, email details, such as the content of the attribute proxyAddresses, will be populated according to the recipient policies (which are also shown on the E-mail Addresses tab of an object in the MMC Active Directory Users and Computers snap-in). Even objects mail-enabled prior to the RUS object creation will be updated once the RUS is created. It also updates attributes such as showInAddressBook, which controls which address books the object will be listed in. Remember, if users are using Microsoft Office Outlook 2003 in cached mode, they would need to download a new copy of the Offline Address Book (OAB--Tools, Send/Receive, Download Address Book) before they'll see additions to any address books.

    I hope this demonstrates the criticality of the RUS and how its proper configuration is vital. Note that in most environments, RUS requires little maintenance and should run "behind the scenes."