MLS welcome messages for DMs and Private groups. Welcome messages only happen when you add a new person to a group and only have to be sent to the new member(s). For groups below ~150 (using Ed25519 or Schnorr keys) the welcome message content fits in a single event. For larger groups, it goes over the 64kb limit. And when you introduce quantum resistant keys, it happens much sooner. https://m.primal.net/LNpy.png