If you are on Mac OS X El Capitan or an earlier version and are receiving a certificate error, it is likely your Keychain is corrupted. You can follow the steps below to try to have it fixed. If you are running the latest Mac (Catalina at this time), DO NOT reset your keychain; instead contact our support for help .Continue reading Certificate error on Mac OS X
Step 1: Open Apple Mail. Click Mail and then select Preferences from the dropdown menu. Continue reading SETUP: POP3 for Apple Mail 3.0
Step 1: Open iMail. Click Mail and then select Preferences from the drop-down menu.
Step 1: Open Apple Mail and click Mail. In the drop-down menu, click Preferences.