How to verify any email with php - php

Question

I am working with a form. Where user enters their email, I can validate the email through regex. But what I need is like this. After searching, I found a solution here. The as it checks the MX record of the email. But still it does not work for me fine, because when I gave a rough email like : ahhhhhhhhhhhhhhhhh#yahoo.com my form accepted it, and when I gave the same email on the other website, it rejected the email. It might be the problem with my logic I don't know, below is my code where I am verifying the email.
if(isset($_GET["saveData"])){
$_appid = $_GET["appid"];
$_name = $_GET["name"];
$_email = $_GET["email"];
$_pass = $_GET["pass"];
$_applink = $_GET["applink"];
function domain_exists($email, $record = 'MX'){
list($user, $domain) = explode('#', $email);
return checkdnsrr($domain, $record);
}
if(!empty($_appid) && !empty($_name) && !empty($_email) && !empty($_pass) && !empty($_applink)){
if(!domain_exists($_email) OR !filter_var($_email, FILTER_VALIDATE_EMAIL)) {
echo "email_prb";
} else{
$sl = "SELECT * FROM fb_data WHERE useremail = '$_email' OR fbappid = '$_appid' ";
$count = $con->query($sl);
if(mysqli_num_rows($count)>0){
echo "exists";
}else{
$in = "INSERT INTO fb_data VALUES(NULL,'$_name','$_email','$_pass','$_applink','$_appid',1,0)";
if ($con->query($in)) {
echo "Inserted";
}
}
}
} else{
echo "empty";
}
}

Answer 1

Kindly Use mysqli or Pdo.. your code is vulnerable to sql injection, try to add mysql escape. but i have rewritten your PHP below without changing query.
Filter validate email will check for the correct email format, so you dont need checking for #. but if you filter the #example.com you need a custom filter for that.
<?php
if(isset($_GET["saveData"])){
$_appid = $_GET["appid"];
$_name = $_GET["name"];
$_email = $_GET["email"];
$_pass = $_GET["pass"];
$_applink = $_GET["applink"];
function domain_exists($email, $record = 'MX'){
list($user, $domain) = explode('#', $email);
return checkdnsrr($domain, $record);
}
if(!empty($_appid) && !empty($_name) && !empty($_email) && !empty($_pass) && !empty($_applink)){
if((!domain_exists($_email)) && (!filter_var($_email, FILTER_VALIDATE_EMAIL))) {
echo "email_prb";
} else{
$sl = "SELECT * FROM `fb_data` WHERE `useremail` = '$_email' OR `fbappid` = '$_appid' ";
$count = $con->query($sl);
if(mysqli_num_rows($count)>0){
echo "exists";
}else{
$in = "INSERT INTO `fb_data` VALUES(NULL,'$_name','$_email','$_pass','$_applink','$_appid',1,0)";
if ($con->query($in)) {
echo "Inserted";
}
}
}
} else{
echo "empty";
}
}
?>

Answer 2

on this part of your code
if(!domain_exists($_email) OR !filter_var($_email, FILTER_VALIDATE_EMAIL))
change the "OR" to ||. Like this
if(!domain_exists($_email) || !filter_var($_email, FILTER_VALIDATE_EMAIL))