A Multi-User Chat room that supports OMEMO MUST be configured non-anonymous and SHOULD be configured members-only.
A participant wanting to send a message to a group chat MUST first retrieve the members list and then fetch the device list for each member (via pubsub and to their real JIDs) and then subsequently fetch all bundles referenced by the device lists.
On join a participant MUST request the member list, the admin list and the owner list as described in XEP-0045 §9.5, XEP-0045 §10.8, and XEP-0045 §10.5 respectively. Those three lists MUST be combined as the recipients of OMEMO encrypted messages. Once joined a participant MUST keep track of affiliation changes that occur in the room. This is both for removals (users getting banned or have their affiliation set to none) and users becoming members, admins or owners.
+On join a participant MUST request the member list, the admin list and the owner list as described in XEP-0045 §9.5, XEP-0045 §10.8, and XEP-0045 §10.5 respectively. The real JIDs from those three lists MUST be combined as the recipients of OMEMO encrypted messages. This includes recipients who are currently offline. Once joined a participant MUST keep track of affiliation changes that occur in the room. This is both for removals (users getting banned or have their affiliation set to none) and users becoming members, admins or owners.
Before sending a message a participant MUST explicitly fetch device lists (if not already cached) for each of the members.