Validações PHP

validate_email.php

<?php
//Checa o e-mail
function check_email_address($email) { 
  // First, we check that there's one @ symbol, and that the lengths are right
   if (!ereg("^[^@]{1,64}@[^@]{1,255}$", $email)) { 
		 // Email invalid because wrong number of characters in one section, or wrong number of @ symbols.
		 return false;
	 } // Split it into sections to make life easier
	 $email_array = explode("@", $email);
	 $local_array = explode(".", $email_array[0]);
	 for ($i = 0; $i < sizeof($local_array); $i++) { 
	 	if (!ereg("^(([A-Za-z0-9!#$%&'*+/=?^_`{|}~-][A-Za-z0-9!#$%&'*+/=?^_`{|}~\.-]{0,63})|(\"[^(\\|\")]{0,62}\"))$", $local_array[$i]))
				{return false;}
		}
    if(!ereg("^\[?[0-9\.]+\]?$", $email_array[1])) {
			// Check if domain is IP. If not, it should be valid domain name
	 		$domain_array = explode(".", $email_array[1]); if (sizeof($domain_array) < 2) {
				return false;
	  			// Not enough parts to domain}
	  			for ($i = 0; $i < sizeof($domain_array); $i++) {
					if (!ereg("^(([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|([A-Za-z0-9]+))$", $domain_array[$i])) {
						return false;
					}
				}
			}
		}
return true;
}
?>