Create a Mailbox-Enabled User
The management of user objects, such as mailboxes, is completely coordinated by Active Directory Users and Computers. When Exchange is installed on a Windows 2000 server, a set of extensions is added to the standard console. This allows you to create an Exchange mailbox for user accounts.
To create a mailbox-enabled user:
Tip If Active Directory Users and Computers does not appear on the Administrative Tools menu, on the Start menu, click Run, type dsa.msc, and then click OK.
Tip If you choose not to add a mailbox when you create a new user account, or if you have already created the user account, you can enable the mailbox after the account is created. This option is available on the Shortcut menu in the details pane listing the user account. For more information on creating Exchange users in Active Directory, click here.