From the Room Overview page select "Send an Email" under your Moderator Tools.
Then send an email to ALL of the People in the room (this includes moderators, participants and explorers). Create a quick subject line, email and then decide if want them to respond to you via email.
You can opt-in to allowing participants to see your email address and reply directly to you.
Warning! Selecting the "use my email address" box your registered email will show to ALL the People you are messaging. If you don't select this option your email address is hidden and they can not respond to you directly.