The following instructions step through the process of reconfiguring Apple Mail on Mac OS X 10.7 and 10.8 after being migrated from Exchange 2007 to Office 365's Exchange Online service. This process involves deleting and setting up the account again with the correct settings.
When trying to send or receive a message after being migrated, an error message will appear. Click Try Later, if this message appears.
From the Mail menu, select Preferences.
Select the account and click on the - button, in the lower left of the window.
Click the Remove button to confirm the account deletion.
Click the + button in the lower left of the window.
Type a name for for the account in the Full Name field.
Select Exchange from the Account Type menu.
In the Incoming Mail Server field, enter outlook.office365.com.
Review the account details, then click Create.
Your account will now be confirgured with the correct settings.