With recent events, I decided to turn on 2-factor authentication for my Google mail. That worked fine. Then I set up application-specific passwords for Mail on my Mac, iPhone, and iPad, and Reeder ...

I use courier-imap and I am currently using authdaemond (included with my courier-imap install) to do authentication.

Their new authentication mechanism which they are calling XOAuth implements OAuth support for the IMAP and SMTP email protocols which traditionally do not support it.