Click your start menu or search bar, type in control
Click on 'Control Panel'
Be sure control panel is set to View by: Category
Click on 'User accounts'
Click on Mail (Microsoft Outlook)
Click on 'Show Profiles'
Click on 'Add..'
Enter a name for the new Profile
Example 'Your Name - O365'
Click on 'Ok'
Enter the first & last name, email address and password to access the account then click on Next.
Click on finish
The last step is to select what profile you want outlook to open when it starts up.
Click the radio bubble, 'Always use this profile.'
Select the profile that you just created from the drop-down list.
Once selected click on OK.
Exit control panel and open outlook. It should load your new profile and begin downloading the email for your mailbox.
