According to Google [1], Gmail supports OAuth over POP, IMAP, and SMTP. However, Thunderbird still does not permit OAuth authentication with Gmail over POP, but only over IMAP. Will this change? Google has announced that they will be turning off simple password authentication over POP and IMAP (what they call "Less Secure Apps" access) in 2020 in favor of enforced OAuth. For users who don't want to change from POP to IMAP, having Thunderbird support OAuth over POP is essential. [1] https://developers.google.com/gmail/imap/imap-smtp