Search-Mailbox command not recognized exchange 2010 sp1 powershell
This problem happens because your account is not a member of the Discovery Management role. Since your account does not have permission to perform searches, Powershell does not import the Search-Mailbox cmdlet.
In ECP, add the account to this role, then close and restart your Powershell session.
Are you running this from the Exchange Management Shell? If you're running from a regular powershell instance, did you remember to import the module? Run get-module to find the name of the exchange module, then run import-module <modulename> to make the commands available.
I used the following to fix the problem:http://www.techieshelp.com/delete-mail-from-multiple-mailboxes/