Orbiting back, It looks to have only been deployed in anger with Google POP. And, in NEWS and the code it's marked as deprecated/unsupported for various reasons. But I would imagine it still works fine on the SMTP side.
for O365 I am using mbsync with the python oauth2 external proxy, because I need to coordinate MH with imap and this mechanism maintains a smallish statefile on the MH side, which tracks the current IMAP message store state. Its "handle this imap store in a way which inc can read from, but inc is now dependent on 3rd party code" hell. A hell I am comfortable in, its the one with Banjos and Accordions but the food is good.
It very probably works, and works well if your inc use-case is POP, and works for SMTP. I haven't tested this.
-G