When I run msextmz.exe, the msextmz.log has entries for mailboxes: Unable find mailbox timezone:Error 0x80004005. Can you tell me what this means and how to resolve it?

Q: When I run msextmz.exe, the msextmz.log has entries for mailboxes: Unable find mailbox timezone:Error 0x80004005. Can you tell me what this means and how to resolve it?
A: This normally represents a permissions failure when the utility tries to access the mailbox. It is also possible that user has only single instance meetings in their mailbox.

Check and make sure that you have granted the account running the tool the appropriate permissions within Active Directory. You may also want to try running from a different machine or with a different administrative account if the problem persists.