Not saying you shouldn't keep doing what works for you but: If visitors knowingly put invalid e-mail addresses 1) do you really need an e-mail address from them

Not saying you shouldn't keep doing what works for you but: If visitors knowingly put invalid e-mail addresses 1) do you really need an e-mail address from them, rather than making the field optional? 2) If so, validation should be done by sending an e-mail with a validation link either way. As others pointed out, for a sanity-check something like /.+@.+/ should be good enough.