As I mentioned to Eric in my support ticket, this issue has been fixed. And I am also not afraid to admit when user error rears its ugly head.
One of the test sites that I've created on my server is successfully sending verification emails. All these files are in their raw, unedited stage (except for the database and Connections files obviously). So this told me that it works on my server.
Somewhere through all the customizations, I must have changed one of the files somehow, in the WA_Universal_Email folder. I replaced the folder, and the users_Registration.php file, with the original files from the zipped PS2 download...uploaded them to my server, and successfully received the emails.
So the moral of the story is, if all else fails, replace the edited files with their originals.
Eric, thank you for all your help.