I would like to second this RFP. I recently received a notification from Google warning me that they are phasing out password authentication, which (in the case of my account) will stop working on May 30. Once that happens, OAuth2 will be the only supported GMail SMTP authentication mechanism. This in turn means sasl-xoauth2 (or equivalent) will become a hard requirement to be able to use GMail SMTP from Postfix, for example.
- Bug#1006888: RFP: sasl-xoauth2 -- XOAUTH2 plugin for... Etienne Dechamps
- Bug#1006888: RFP: sasl-xoauth2 -- XOAUTH2 plugi... Jameson Graef Rollins
- Bug#1006888: RFP: sasl-xoauth2 -- XOAUTH2 plugi... Daniel Kahn Gillmor