Why do I see “admin_policy_enforced”, “App Blocked”, “unverified app” or “not approved” error/warning when logging in to Gmail?

Google is asking K-9 Mail to go through a new verification process and has introduced some additional requirements that weren’t needed before. We’re working hard to meet these requirements, but unfortunately, it’s not something we can resolve right away. For those interested, more technical details can be found in issue 8598. In the meantime, here are some workarounds:

• If you are using K-9 Mail, try Thunderbird for Android.
• Try making use of app-specific passwords. Note however there are a few common scenarios where Google does not allow use of app passwords. See https://support.google.com/accounts/answer/185833 for more details.
• Another workaround may be logging in on Thunderbird Desktop, and then afterward trying to log in on Thunderbird for Android.

Workaround for Google Advanced Protection errors such as “admin_policy_enforced”

If you see an admin_policy_enforced message, then your administrator has Google Advanced Protection enabled for your Google Workspace or unverified apps have been disabled. Unfortunately the only workaround at the moment is to ask your administrator to disable Google Advanced Protection by following the steps in Google's documentation: Control which third-party & internal apps access Google Workspace data. Your workspace Administrator may also be able to introduce an exception for Thunderbird for Android.

If you are in control of your workspace, you can temporarily remove yourself from the Google Advanced Protection program, sign in to Thunderbird for Android, and then re-enroll yourself. Note however, when a background authentication needs to be renewed, you may be required to repeat the process.

We are working on becoming part of this program in the future, so this workaround will not be required.