The managed folder assistant is a Microsoft Exchange Mailbox Assistant that creates managed folders in users’ mailboxes and applies managed content settings to them. When the managed folder assistant is running, it processes all of the mailboxes on a server. If the managed folder assistant does not finish processing the mailboxes on the server during the time that you have scheduled, it automatically resumes processing where it left off the next time it runs. There is one managed folder assistant for each server

Get-ExchangeServer | Where { $_.AdminDisplayVersion.ToString().SubString(0, 10) -eq “Version 8.” `

-and $_.ServerRole -eq “Mailbox” } |

ForEach { Set-MailboxServer -Identity $_.Identity `

-ManagedFolderAssistantSchedule “Sun.1:00 AM-Sun.3:00 AM”, `

“Mon.1:00 AM-Mon.3:00 AM”, “Tue.1:00 AM-Tue.3:00 AM”, `

“Wed.1:00 AM-Wed.3:00 AM”, “Thu.1:00 AM-Thu.3:00 AM”, `

“Fri.1:00 AM-Fri.3:00 AM”, “Sat.1:00 AM-Sat.3:00 AM” }

http://technet.microsoft.com/en-us/library/bb123958.aspx