Message Receipts are sent for group chats
According to XEP-0184 5.3
It is NOT RECOMMENDED to request a receipt when sending a content message of type "groupchat" in a Multi-User Chat (XEP-0045) [7] room because the logic for determining when a content message is truly "received" by all of the room occupants is complex, and because the sender would receive one ack message from each occupant of the room, thus significantly increasing the number of stanzas sent through the room. Currently it is set and then reflected back by the MUC, and then acknowledged back to itself generating excessive roundtrips:
(09:50:20) jabber: Sending (ssl) (me@ruff.mobi/chatty): <message type='groupchat' id='purpledb8b7b0d' to='wiaks2qes@conference.xmpp.zone'><body>olah</body><request xmlns='urn:xmpp:receipts'/></message>
(09:50:20) jabber: Recv (ssl)(315): <message type="groupchat" id="purpledb8b7b0d" to='me@ruff.mobi/chatty' from='wiaks2qes@conference.xmpp.zone/me'><request xmlns='urn:xmpp:receipts'/><body>olah</body></message>
(09:50:20) jabber: Sending (ssl) (me@ruff.mobi/chatty): <message to='wiaks2qes@conference.xmpp.zone/me'><received xmlns='urn:xmpp:receipts' id='purpledb8b7b0d'/></message>
(09:50:21) jabber: Recv (ssl)(246): <message to='me@ruff.mobi/chatty' from='wiaks2qes@conference.xmpp.zone/me'><received id='purpledb8b7b0d' xmlns='urn:xmpp:receipts'/><x xmlns='http://jabber.org/protocol/muc#user'/></message>
(sm.puri.Chatty:48153): chatty-xeps-DEBUG: 09:50:21.476: Received ackn for node_id: purpledb8b7b0d