Setting up an App Password for Gmail

An App Password is a 16-character password generated by Google that gives what Google considers to be a less-secure app or program or device permission to access your Google account (iPhones and iPads with iOS 11 or up don't require App Passwords and can use "Sign in with Google" instead). You can generate an App Password for Claws Mail and use that password instead of your Google account password only in Claws Mail. Note that your Google account password (in combination with Google's required 2-Step Verification) will still be used for signing in to Google with any browser or mobile device.

Instructions:
    1. Sign in to Google: https://accounts.google.com/signin
    2. Open the Security page: https://myaccount.google.com/security
    3. Click "App Passwords".
    4. Click "Select app".
    5. Choose "Other (Custom name)".
    6. Type in "Claws Mail" or the name you'd like to use.
    7. Click "GENERATE" to create a 16-character App Password.
    8. Copy the App Password onto the clipboard.
    9. Open Claws Mail.
    10. Click the "Configuration" menu in Claws Mail.
    11. Choose "Preferences for current account…" from the menu.
    12. Paste the App Password you copied from Google into the "Password" field in the "Basic" tab of your Gmail account in Claws Mail. That tab should have already opened or you can click it in the left pane).
    13. Click "Apply".
    14. Click "Send" in the left pane to open the "Send" tab.
    15. Paste the App Password you copied from Google into the "Password" field.
    16. Click "Apply" and "OK" in Claws Mail.
    17. Close Claws Mail.
    18.  Click "Done" in Google.
    19. Sign out of your Gmail account.

If you forget your App Password and need it again or would like to change it, you can delete the one that you have stored in the "App Passwords" section by clicking the trash icon to the right of it and then repeating the steps above to generate and use a fresh one.

See also:
    • About App Passwords: https://support.google.com/accounts/answer/185833
    • About 2-Step Verification: https://support.google.com/accounts/answer/185839