if you are facing difficulties ATT Email not working on iPhone through POP/ IMAP protocols then you should check the steps below:

• Make sure your phone (Android or iPhone) is not in airplane mode.
• Confirm that your phone has a smooth wifi or mobile data connection.
• Check the storage space in your phone and make sure it is not running low.
• Remove all such applications that can conflict with AT&T email.
• Recheck the IMAP/ POP settings that you have installed on your device.
• Switch to POP in case you are using IMAP to load AT&T email and vice versa.
• Restart your device multiple times and see if this resolves the AT&T not working problem.