How to fix Apple iCloud IMAP authentication failure?
Apple requires the use of app-specific passwords for connecting iCloud accounts to third-party email apps, instead of using your main Apple ID password. If you have previously only used Apple Mail on Mac or iOS, you haven’t been required to do this procedure, so you may need to take the following steps:
- Follow these steps to enable Two-Factor authentication for your Apple ID.
- Follow these steps to generate an app-specific password for Missive.
If you already use non-Apple apps for your email, you most likely have already completed step 1, so only step 2 must be done.