http://blogs.technet.com/provtest/archive/2009/06/04/hosted-email-2007-import-importmailbox-will-mess-up-your-customerassets-table.aspxFor those who are doing the migration from HMC 3.5 to HMC 4.0 using the HMC 4.0 Migration Kit, you may want to take note of this. One of the tasks executed by the Hosted Email 2007 Import::ImportMailbox procedure is creating the mailbox GUID asset foren-USCommunityServer 2.1 SP1 (Build: 61025.2)