The component "Microsoft Exchange Messaging and Collaboration Services" cannot be assigned the action "Remove" because:
- One or more users currently use a mailbox store on this server. These users must be moved to a mailbox store on a different server or be mail disabled before uninstalling this server.
Thanks for leaving me the fun part of trying to guess who you think still has a mailbox.
Fortunately, there's an easy way to do this.
Let's say your server name is EXCH01.
- Launch Active Directory Users and Computers.
- In the navigation pane, right-click on your domain and select Find from the context menu.
- In the Find Users, Contacts, and Groups window, click the Advanced tab.
- Click the Field button, point to User, and then select Exchange Home Server.
- Set the Condition field to Ends With.
- Enter the Exchange mailbox server you're decommissioning in the Value field (in our example, EXCH01).
- Click Add.
- Click Find Now.
- Once the list of users is displayed, you can right-click on the user, select Exchange Tasks, and then select Remove Exchange Attributes from the list of options. Acknowledge the warning, and repeat for each user.
- Restart Exchange setup.