I'm interested to the opportunity to provide a blacklist feature for this module. For this reason I wrote the code necessary to allow site administrators to input different domain inside a blacklist form. The email address with these domain will be automatically rejected during user registration. A regexpr avoid to insert faked domain inside blacklist form. I hope it's interesting. Regards.

Files: 
CommentFileSizeAuthor
email_verify.patch2.89 KBabertulla

Comments

note that one can also blacklist e-mail addresses via
access rules in core, i.e.: admin/user/rules/add

As is, I have would have to vote against this. That variable could get really huge. I think skizzo's suggestion is far better (it is a core feature). There is a simple function (whose name escapes me at the moment) to check whether or not someone is allowed to post.