note 92728 deleted from function.preg-match by danbrown

Note Submitter: suit dot 2009 at rebell dot at ---- Reno's expression is still wrong. The domain-part may contain lots of characters for IDN. IP adresses in the domain part are allowed. In local-part are more characters allowed too but specific combinations are forbidden. Check RFC 2822 and RFC 2821. "foo bar"@example.com is valid foo\@bar@example.com is valid $?^_`.!#{|}%&'*+-/=~@example.com is also valid e-mail-address (ok, quite uncommon example) but foo.@example.com is invalid, dot at beginning and end of the string is not allowed - but Reno's expression would match. an e-mail adress should not be longer than 256 characters (or 64 in local part, 255 in domain part) since its limited by SMTP - check RFC 5321 Of course you should check RFC 2606 (Section 3) too - domain.tld or host.tld are not good as example-domains. Use example.com / org / net (for domains) or .invalid / . example (for top level domains).