Error in SMTP settings - eNewsletter

Trying to install eNewsletter plugin on test location of a client's site at http://www.heartsandlaserbeams.com/dev/lovebites and everything's going rad. Except setting up the SMTP settings of the newsletter plugin, which is the very last thing I have to get to work before this baby's done.

Check out the screengrab, any ideas how to fix? I've been on the phone with Hostgator for an hour, and they've exhausted every possible problem it could be on their end.

The only way they could really get to the bottom of whether it was a hosting problem was with me giving them a login and pass to use, and I'm pretty sure that's the case here, as well. Is there someone I can shoot a login and pass to so you guys can take a look?

Thanks!