@[email protected] I think I tried something like that already. A single actor in the "to" field and had the mention tag. Maybe you have to have the user atting (@) in the content? I see some other engines than Mastodon use other fields as well.

Hmm, is there a way in Mastodon to see the ActivityPub request json directly maybe? So you could compare a public message to a DM.

I have been trying to figure out how to send a DM using #ActivityPub but I have still not found any clear instructions on what the message should contain for it to be a proper DM.