[Users] claws-mail with OAuth2 IMAP O365

[David Fletcher]

Sorry, yes, I have misunderstood the question.

You can extract the ClientID from the Thunderbird sources and just use
that in Claws Mail. That way the server just sees the client as an
instance of Thunderbird. Get the source package for your distribution
and look in the file /comm/mailnews/base/src/OAuth2Providers.jsm within
the unzipped sources.

This page actually gives you the information too:
https://blog.thunderbird.net/2023/01/important-message-for-microsoft-office-365-enterprise-users/

Best regards, David.