I have prepared a backport of claws-mail, and have uploaded it - It's in the backports NEW queue, so I don't know how long it will take before getting through (It is out of my control).
If there is any problems with the package, I'll fix them and get it through the NEW queue again, if necessary, so you will get a new(er) claws-mail package soon enough which supports the gmail OAUTH2 business. (I am running a backported version of claws for some time - for me it works just fine). -- Andreas Rönnquist gus...@debian.org
