一个非常不错的Email地址验证函数

<?php
 function valid_email($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;
 }
 ?>