Won't let new user join

[joanne862]

I upgraded to 3.7 yesterday.
I've just had an email from a user trying to sign up, but it wouldn't let them, they received a message stating that their e-mail address was denied.
Email is ****@comcast.net

They're not on the banned email or IP list. We've had comcast users sign up before with no problem, so I can't work out why they are getting that message.

Thanks

[Wayne Luke]

Check your censored word list for the first four letters of the email address.