Remoting and Invoke-command


I have a DAG with 9 members, each with 10 active DBs (90 DBs total).

My problem is: Sometimes I need to search through all mailboxes for specific mails and delete it.

If i run: Get-mailbox | search-mailbox..... Everything works fine. But takes very long time. (10.000+ MBXs)

Is there a way to tell each server to search its own active DBs for content?

I have tried with Invoke-command but getting auth errors, message is:

"Active Directory operation failed on . The supplied credential for '<domain>\<admin>' is invalid."

Do I have to use credssp or is there another way?