note 24084 modified in function.preg-match by tularis

This preg-based function checks whether an e-mail address is formally valid. It works with all top level domains including the new ones (.biz, .info, .museum etc.) and the special ones (.arpa, .int etc.) as well as with e-mail addresses based on IPs (e.g. webmaster@123.45.123.45). function is_email($email){ return(preg_match("/^[-_.[:alnum:]]+@((([[:alnum:]]| [[:alnum:]][[:alnum:]-]*[[:alnum:]])\.)+(ad|ae|aero| af|ag|ai|al|am|an|ao|aq|ar|arpa|as|at|au|aw|az|ba|bb| bd|be|bf|bg|bh|bi|biz|bj|bm|bn|bo|br|bs|bt|bv|bw|by| bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|com|coop|cr| cs|cu|cv|cx|cy|cz|de|dj|dk|dm|do|dz|ec|edu|ee|eg|eh| er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gh|gi| gl|gm|gn|gov|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht| hu|id|ie|il|in|info|int|io|iq|ir|is|it|jm|jo|jp|ke| kg|kh|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls| lt|lu|lv|ly|ma|mc|md|mg|mh|mil|mk|ml|mm|mn|mo|mp|mq| mr|ms|mt|mu|museum|mv|mw|mx|my|mz|na|name|nc|ne|net| nf|ng|ni|nl|no|np|nr|nt|nu|nz|om|org|pa|pe|pf|pg|ph| pk|pl|pm|pn|pr|pro|ps|pt|pw|py|qa|re|ro|ru|rw|sa|sb| sc|sd|se|sg|sh|si|sj|sk|sl|sm|sn|so|sr|st|su|sv|sy| sz|tc|td|tf|tg|th|tj|tk|tm|tn|to|tp|tr|tt|tv|tw|tz| ua|ug|uk|um|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye| yt|yu|za|zm|zw)|(([0-9][0-9]?|[0-1][0-9][0-9]| [2][0-4][0-9]|[2][5][0-5])\.){3}([0-9][0-9]?| [0-1][0-9][0-9]|[2][0-4][0-9]|[2][5][0-5]))$/i", $email)); } (Note that the line-broken regular expression is one long string without any space or new-line characters!) Returns true if the address is valid, false otherwise. --was-- [Editor's note: parse_url() will be simpler and faster, but it is always good to know the actual regex for cases that need a particular tweak] This preg-based function checks whether an e-mail address is formally valid. It works with all top level domains including the new ones (.biz, .info, .museum etc.) and the special ones (.arpa, .int etc.) as well as with e-mail addresses based on IPs (e.g. webmaster@123.45.123.45). function is_email($email) { return(preg_match("/^[-_.[:alnum:]]+@((([[:alnum:]]| [[:alnum:]][[:alnum:]-]*[[:alnum:]])\.)+(ad|ae|aero| af|ag|ai|al|am|an|ao|aq|ar|arpa|as|at|au|aw|az|ba|bb| bd|be|bf|bg|bh|bi|biz|bj|bm|bn|bo|br|bs|bt|bv|bw|by| bz|ca|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co|com|coop|cr| cs|cu|cv|cx|cy|cz|de|dj|dk|dm|do|dz|ec|edu|ee|eg|eh| er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gh|gi| gl|gm|gn|gov|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht| hu|id|ie|il|in|info|int|io|iq|ir|is|it|jm|jo|jp|ke| kg|kh|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls| lt|lu|lv|ly|ma|mc|md|mg|mh|mil|mk|ml|mm|mn|mo|mp|mq| mr|ms|mt|mu|museum|mv|mw|mx|my|mz|na|name|nc|ne|net| nf|ng|ni|nl|no|np|nr|nt|nu|nz|om|org|pa|pe|pf|pg|ph| pk|pl|pm|pn|pr|pro|ps|pt|pw|py|qa|re|ro|ru|rw|sa|sb| sc|sd|se|sg|sh|si|sj|sk|sl|sm|sn|so|sr|st|su|sv|sy| sz|tc|td|tf|tg|th|tj|tk|tm|tn|to|tp|tr|tt|tv|tw|tz| ua|ug|uk|um|us|uy|uz|va|vc|ve|vg|vi|vn|vu|wf|ws|ye| yt|yu|za|zm|zw)|(([0-9][0-9]?|[0-1][0-9][0-9]| [2][0-4][0-9]|[2][5][0-5])\.){3}([0-9][0-9]?| [0-1][0-9][0-9]|[2][0-4][0-9]|[2][5][0-5]))$/i", $email)); } (Note that the line-broken regular expression is one long string without any space or new-line characters!) Returns true if the address is valid, false otherwise. http://www.php.net/manual/en/function.preg-match.php