1.Open the Exchange System Manager.
2.Open the Tools container.
3.Select Mailbox Recovery Center.
4.Click the Action menu and select Add Mailbox Store.
5.Provide the name of the mailbox store. Click OK.
6.In the details pane, select each mailbox(es) which should be resolved.
7.Click the Action menu and select Resolve Conflicts.
8.The Exchange Mailbox Conflicts Resolution Wizard launches.
9.Click Next on the Exchange Mailbox Conflicts Resolution Wizard Welcome screen.
10.On the User Matching page, select which Active Directory account(s) should be resolved, and then click Next.
11.A message should be displayed, indicating that sufficient information exists to correct the issue and prepare the account for reconnection.
12.Select Finish

Online