I used to try to do this in my django-registration package, but eventually gave up on it because maintaining an up-to-date list of all possible domains and other patterns was not feasible. I expect the same would be true with Django — it would require frequent updates to the list of domains/patterns to block, and people would complain that the updates weren’t fast enough, because Django only releases once a month (and that’s assuming updates to the blocked email list would be considered for inclusion in the monthly bugfix releases, rather than only at feature release updates).
So I expect this isn’t something Django could or should do.