Check email format using php

 
function is_email($email){
    if(filter_var($email, FILTER_VALIDATE_EMAIL))
        return true;
    else
        return false;
}
 

 
function checkMail($email){
    $correct = 0;
     if ((strlen($email) >= 6) && (substr_count($email,"@") == 1) && (substr($email,0,1) != "@") && (substr($email,strlen($email)-1,1) != "@")){
       if ((!strstr($email,"'")) && (!strstr($email,"\"")) && (!strstr($email,"\\")) && (!strstr($email,"\$")) && (!strstr($email," "))) {
           if (substr_count($email,".")>= 1){
              $term_dom = substr(strrchr ($email, '.'),1);
              if (strlen($term_dom)>1 && strlen($term_dom)<5 && (!strstr($term_dom,"@")) ){
                 $antes_dom = substr($email,0,strlen($email) - strlen($term_dom) - 1);
                $caracter_ult = substr($antes_dom,strlen($antes_dom)-1,1);
                if ($caracter_ult != "@" && $caracter_ult != "."){
                   $correct = 1;
                }
             }
          }
       }
    }
 
    return $correct;
}