Please do NOT use regex to “validate” email addresses. You’re almost certainly guaranteed to get it wrong, as the RFC’s for what constitutes a “valid” email address are extremely complex.
I’ve lost track of the number of times I’ve had a site’s validation system reject a perfectly valid email address.
The expression given misses many valid characters, doesn’t understand quoted local email parts, comments, or ip address for domains.
A regular expression can only act as a rudimentary filter. The problem with regular expressions is that telling someone that their perfectly valid e-mail address is invalid (a false positive) because your regular expression can’t handle it is just rude and impolite from the user’s perspective.
Not to mention the fact that you probably also just lost a customer.
For more, see:
https://stackoverflow.com/questions/2049502/what-characters-are-allowed-in-an-email-address#2049510
