Miscellany

<?php

	function valid_email($email) {
	
		$atom = '[-a-z0-9!#$%&\'*+/=?^_`{|}~]';    // allowed characters for part before "at" character
		$domain = '([a-z]([-a-z0-9]*[a-z0-9]+)?)'; // allowed characters for part after "at" character

		$regex = '^' . $atom . '+' .        // One or more atom characters.
		'(\.' . $atom . '+)*'.              // Followed by zero or more dot separated sets of one or more atom characters.
		'@'.                                // Followed by an "at" character.
		'(' . $domain . '{1,63}\.)+'.        // Followed by one or max 63 domain characters (dot separated).
		$domain . '{2,63}'.                  // Must be followed by one set consisting a period of two
		'$';                                // or max 63 domain characters.
		
		if (strlen($email) == 0) {
			return false;			
		}
		if (eregi($regex, $email)) {
			return true;
		}

		return false;
	}

?>