How do I enable a user for instant messaging?

Start the Microsoft Management Console (MMC) Active Directory Users and Computers snap-in (Start, Programs, Administrative Tools, Active Directory Users and Computers).

Expand the domain/organizational unit (OU) that contains the user you want to enable.

Right-click the user.

From the context menu, select Exchange Tasks.

Click Next.

Select Enable Instant Messaging, and click Next.

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Select the Instant Messaging Home Server by clicking Browse. Then select the IM domain name from the drop-down list. Click Next.

Click Finish on the summary screen.