1. Click on Tools then select Account Settings from the menu.
2. Find the email account you are checking, the second column should be “Type” and it will tell you if it’s POP or IMAP.
3. If you don’t see it there, go ahead and double-click the account.
4. In the new window (Titled “Change E-mail Account”), look under Server Information and find Account Type. It will say POP3 or IMAP.
For Thunderbird, the instructions are similar.
1. Click on the “Hamburger” in the upper right corner of the window.
2. Select Preferences then select Account Settings.
3. In the left pane, click on Server Settings.
4. In the right pane, find Server Type and it will say IMAP or POP3.