检查电子邮件的工作对于一些注册类的网站来说非常有必要，下面有个不错的函数，大家可以参考下

 代码如下: function is_valid_email_address($email){  $qtext = '[^//x0d//x22//x5c//x80-//xff]';  $dtext = '[^//x0d//x5b-//x5d//x80-//xff]';  $atom = '[^//x00-//x20//x22//x28//x29//x2c//x2e//x3a-//x3c'.  '//x3e//x40//x5b-//x5d//x7f-//xff]+';  $quoted_pair = '//x5c[//x00-//x7f]';  $domain_literal = "//x5b($dtext|$quoted_pair)*//x5d";  $quoted_string = "//x22($qtext|$quoted_pair)*//x22";  $domain_ref = $atom;  $sub_domain = "($domain_ref|$domain_literal)";  $word = "($atom|$quoted_string)";  $domain = "$sub_domain(//x2e$sub_domain)*";  $local_part = "$word(//x2e$word)*";  $addr_spec = "$local_part//x40$domain";  return preg_match("!^$addr_spec$!", $email) ? 1 : 0;  }