Office 365 will not support a MAPI connection from Outlook 2003 since Public Folders are no longer available. For BPOS, this was possible because of the add-in developed to allow for Outlook 2003. Outlook 2003 requires Public Folders to be available
in order to connect to Exchange.
On the other hand, IMAP/POP should function normally if you choose to configure that. The configuration info will be in each user's OWA under Options in Office 365.
If all else fails, your users can utilize OWA.
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