validateEmail.php

<?php
 
function validateEmail($email)
{
    if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
        throw new InvalidArgumentException("Invalid email");
    } else {
        $domain = end(explode('@', $email));

        if (!checkdnsrr($domain, 'MX')) {
            throw new InvalidArgumentException("Invalid email");
        }

        return true;
    }
}

$emails = array("[email protected]", "[email protected]");

foreach ($emails as $email) {
    try {
        if (validateEmail($email)) {
            echo "Valid email" . PHP_EOL;
        }
    } catch (InvalidArgumentException $e) {
        echo $e->getMessage() . PHP_EOL;
    }
}