In the persons rubric you will find a list of all room participants. Presenters and contact persons are marked with corresponding icons. Even if the email address is hidden, you can send an email to other people about the room. If you call up a person's entry, you may see additional contact details and information provided for that room.
By the way, in this rubric you will also find those persons who are still waiting for activation by moderators or are locked, i.e. do not have the status "user". To view this list, change the selection of the displayed status group in the menu "Restrict list" under "Status".