some spammers jump in to public mucs, pollute and jump out immediately.

this module helps prosody administrator to log who joined the room.

to add:

put module mod_muc_jid_logger.lua in to your modules directory.

Component "conference.example.com" "muc"
    modules_enabled = {
        -- other modules
        "muc_jid_logger";
    }

/etc/init.d/prosody reload