I have inherited an Exchange environment running Exchange 2010. The default SystemMaiboxes are located in the Users OU. However, there are also 3 other SystemMailboxes located in the MS Exchange System Objects OU. Their HomeMTA is pointing to the Deleted Objects, and they are not listed as Arbitration mailboxes. I believe this environment was upgraded twice, 2003-2007, then 2007-2010.
How can I verify they are not needed and what is the proper procedure for removing them.