Ruby Forum Rails Spinoffs (closed, excessive spam) > how can i restrict for email

hello all
i have a problem of email validation
my question is that how can i restrict anybody to create email address 
like
this
r@r.r or
a@a.a
b@b.b
similar combination of others .
any point and suggestion appreciated.
regards
ravi

This is a Javascript question and has nothing to do with Prototype.
You'll probably find better answers in the appropriate place.