First off, this is not a temporary block due to a surge of spammers.
Secondly, nowhere on the website does it mention that free email accounts are blocked.
Thirdly, AOL, Yahoo!, Gmail... all of these main email usage accounts are blocked.
I registered with two different email accounts and the only message I receive is:
"This email address has been banned"
There is a thread on this forum I really want to reply to (I have the EXACT same problem).
The funny thing is, I don't necessarily have a problem with blocking free email accounts; however, no-where does it mention this on the site. I personally emailed theme using the "Contact Us" form, and surprisingly they replied back.