How do I add an additional mailbox to an existing Outlook profile View The Full Article 1. From Outlook, rightclick on the name of your mailbox then left click on Properties for Mailbox Last, First . . . . Depending on the version of Outlook being used, it may say Outlook Today . . . Mailbox . . . or simply Last, First 2. When the Properties window appears, click the Advanced button 3. You will now see an Microsoft Exchange Server window with 45 tabs across the top Depending on the version of Outlook being used. Click on the Advanced tab, then click on the Add . . . button. 4. On the Add Mailbox window, type in the name of the mailbox to be added and click OK. You can enter the full or partial name. If you enter a partial name, the Global Address List will appear and prompt you to select the correct entry if more than one mailbox matches the text you entered. 5. You will now see the name of the mailbox added to the Open these additional mailboxes: Window. If you need to add another mailbox, you can click the Add . . . button again. Otherwise, click OK to finish adding the mailbox to the existing Outlook profile. 6. You will return to the main Outlook view, and you should now see the mailbox in your folder view. To view the entire mailbox, click on the to the left. This will fully expand the mailbox to show all folders. 7. Once the mailbox has been expanded, the folders will be viewable and you should see a to the left of the mailbox name now. 8. You can now work from the additional mailbox just as you would with your personal mailbox. Note: Any items you send FROM Sent On Behalf Of the additional mailbox will appear in your personal Sent Items folder.