Blacklisting domains for emails

A new form of "spam" registrations are normal users using disposable trash emails.

Captchas and submitter IP blacklisting are obviously no solution to prevent this, as well as DNS checks and double opt-in procedures.

So our feature request is to implement a blacklist validation option like "not on blacklist" with a maintainable blacklist for mail domains in the global settings. How about that? :)

There are lots of lists of those mail providers existing (e.g. http://www.articlevoid.com/computers-and-technology/coding/how-to-block-disposable-email-addresses/), but there is no simple solution to integrate such a blacklist as validation in a rs form field :(