Google lets you put any number of periods in your gmail address, and it ignores all of them when receiving mail for you.
Try it; it's fun!
Spammers have taken advantage of this, unfortunately, to spam more and more easily.
If you see a Gmail address with about as many periods as letters, it is probably a spammer. If that address turns up twice, differing only by the number or placement of periods, it is pretty certainly a spammer.
Wouldn't it be nice if blocking one such address prevented any others from registering? If there isn't already a module for that (or almost that?), i'll make one.
This module does not automatically block registration with such addresses, but once you block one address, it will block any more from registering.
The only existing modules i can find in the general idea space, searching the web and d.o for drupal module block all variations of google address and block email from registering, were not suitable for extension.
This would be a Drupal 7 module, though i would welcome patches to backport it.
Background: Notes and links related to blocking gmail address variants.
Am i wrong? Is this out there already, or an appropriate module to offer a patch to?