My phone is asking for a password for IMAP in order to open mail. I don't know what the password is. What do I do?

Your IMAP password is the email password that you use to access your email.

So whether it is from Apple, Google, Yahoo, or whoever, it would be the password you would enter if you wanted to check your email in a browser, for example.

So, if you do not know your email password, contact your email provider to reset your email password.