Configure Postfix to Send Mail Using Gmail and Google Apps on Debian or Ubuntu

[Rajakavitha1]

Update the guides based on comments in DisQus:

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In light of the recent announcement that google is disabling access to less secure apps in early 2021: https://gsuiteupdates.googleblog.com/2019/12/less-secure-apps-oauth-google-username-password-incorrect.html
is there some other method to allow postfix to forward outgoing emails through gmail?
I guess the simple alternative here is just to use a regular, non-gsuite, google account for the forwarding.

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Great tutorial, but Google is disabling username and password access on February 15, 2021. So how do you setup Postfix to use OAuth instead of a username and password?

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I'd be interested to see an extension of this tutorial to properly set up postfix when using DKIM as I think the DKIM signing needs to happen on the postfix side.

[freekdk]

Using DKIM does not solve the problem to send e-mail using postfix via gmail.com to an address outside gmail.com.
A guide for the setup is on http://mmogilvi.users.sourceforge.net/software/oauthbearer.html, but it is not really an easy to follow recipe. I am working on it, most likely I will publish it first on https://en.opensuse.org/Mail_server_HOWTO or on https://forums.opensuse.org/showthread.php/570725-Postfix-not-able-anymore-to-send-email-via-gmail-com