After you migrate to Exchange Online you MUST empty your Outlook's auto-complete list to ensure that all your emails get addressed using Exchange Online's University-wide address book. If you do not do this, emails addressed using your Outlook's auto-complete list will not get delivered; you will not get a delivery failure notice.
Outlook on PC
- Open Outlook.
- From the File menu, select Options.
- Click the Mail menu item.
- In the Send messages section, click the Empty Auto-Complete List button.
- Close the Outlook Options window.
Outlook for Mac
- In Outlook, select your Exchange Online mailbox folder in the left-hand navigation pane.
- Right-click (Command-click) to open the menu and select Properties.
[Alternative method: with your folder highlighted, go to File > Folder > Properties]. - Click on the Empty Cache (Warning - there is no turning back!).
- Click OK to close the window.