Does someone know how the #fediverse works? How transitive is it?
Suppose server S1 federates with server S2, which federates with server S3, but S1 does not federate with S3. User U1 on server S1 sends message M1. User U2 on server S2 responds with message M2.
Can user U3 on server S3 see both messages M1 and M2, or only message M2, or none of them? Can user U3 reply to message M1 or M2 or both? If yes, will user U1 see it?