> it seem about 5% of all registration forms use a regex similar to .*@[a-z0-9]\.[a-z]{2,4} That matches @0.ab, but not mail@example.com. I think you mean: .+

> it seem about 5% of all registration forms use a regex similar to .*@[a-z0-9]\.[a-z]{2,4} That matches @0.ab, but not mail@example.com. I think you mean: .+@[a-z0-9]+\.[a-z]{2,4}