disabling mailbox for the Built-in Administrator account

anyone see any issues with disabling the Built-in Administrator account's mailbox in Exchange 2007.  I don't want to remove because that will delete both the account in AD and the mailbox.  I am doing this because we have a hybrid exchange environment and I am moving all mailboxes up to Office 365 and you can't move up a built-in administrator account.
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FOXActive Directory/Exchange EngineerCommented:
you cannot delete built-in administrator account

You may disable its associated mailbox, it should not make any difference

The tasks that admin account is able to do because it is member of Exchange organization management group
Further why you want to move built-in administrator account to O365?

O365 has separate global admin available for management
jkimzlgAuthor Commented:
There is a administrator mailbox on my Exchange 2007 server.  I'm trying to get it off so I can uninstall Exchange 2007.  I am only asking if it's ok to disable the administrator's mailbox and leave the administrator AD user account alone.
Yes, you can and need to disable mailbox, otherwise exchange won't be uninstalled

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