If you have an IMAP, or HTTP (Gmail, Outlook.com etc.) account, mail is not generally stored on your computer. All email remains on the mail server until you delete it.
- Open Outlook.
- Click the File tab > Account settings.
- Highlight your current POP3 account and click Change.
Note: The window that opens will tell you what type of email account you have. (Look under Type.)
- Choose More settings and click on Advanced.
- You should see a check box titled: Leave a copy of messages on the server.
- Checking the box will enable Leave a copy of the message on the server.
If you would like to know more about different email account types, see Introduction to e-mail account types.