Captivate 5 - Send for Review e-mail error

I am trying to send a project out for review in Captivate 5.  I want to store files on a internal server (not acrobat.com).  Each time I get to the send e-mail stage in the process it fails and asks me to "Enter a valid e-mail Id"   The e-mails I have entered are indeed valid and correct, so the error must refer to something else.

Any ideas of how to solve this problem?

Here's some more background information: the send for review process works fine on this machine in Captivate 4.  I have made sure that I set up a free account on Acrobat.com and signed the terms of agreement, even though I don't want to use this service.