Please take note of two important points:
1. Instead of your MJN userID, you will be using your full primary email address to login to Outlook after the migration. No changes on how you log into your computer and other applications.
2. If you are accessing MJN webmail, the new URL will be http://outlook.office365.com after the migration.
Please carefully read the attachment and refer to the Exchange Online FAQs for additional information.