Channels and group chats

In semi-anonymous MUCs, only moderators can see your Jabber ID (JID) - so only moderators can DM you, add you as a contact, or invite you to other MUCs. This helps protect members against spam and harassment from other members.

If you want to DM a member of a semi-anonymous MUC (without having their JID), you can use whispers (also known as MUC PMs) to exchange JIDs. Note that whispers may be disabled in some MUCs.

In non-anonymous MUCs, your JID is visible to all members of the MUC. Some MUC features - like read markers and end-to-end encryption - are only available in non-anonymous MUCs.

Anyone can join a public MUC (also known as a "channel"), whereas private MUCs (also known as "group chats") are invite-only.

Most public channels on the XMPP network are also semi-anonymous. If you try to join a non-anonymous public channel, some clients (e.g. Monocles Chat, Cheogram, and Conversations) will warn you that "joining this channel will make your JID public."

Some channels may also be moderated - that means new members can't send messages by default, and mods have to grant them voice manually. This is very effective against spam.

In moderated channels, you can ask for voice by whispering to the moderators. Monocles Chat and Gajim (among others) have special support for easily sending a voice request to all moderators of a channel.