Email Not Working

[AliNicks]

I was a co-host for a 4 day webinar last night.

1. One of our registered attendees emailed me and said that she wasn't able to get in because: This meeting is for authorized registrants only.  Please enter another email address.

When I looked at the list of people that had signed up, her name and email were both spelled correctly. Can someone tell me what the problem might be and some remedies for this.

2. We also had some people register at the last minute, and because they weren't on the list given to me, I removed them from the Waiting Room, keeping them from getting back in. Will this keep them from being able to join for the rest of the sessions? If so, what needs to be done to get them in?

Thanks in advance for your help!