You can't use MAPI to set up Outlook 2003 for use with Exchange Online
When you try to use Messaging API (MAPI) to set up Microsoft Office Outlook 2003 to connect to Microsoft Exchange Online in a Microsoft Office 365 environment, the MAPI connection might not work.
Outlook 2003 isn't a supported email client for connecting to Exchange Online mailboxes by using MAPI in Office 365.
Note Outlook 2003 is supported for connecting to Exchange Online mailboxes by using the Post Office Protocol (POP) or Internet Message Access Protocol (IMAP) protocols.
Article ID: 2449616 - Last Review: 10/08/2014 16:05:00 - Revision: 27.0
Microsoft Exchange Online
- o365 o365a o365e o365p o365022013 o365m KB2449616