Email verification with PHPMailer without sending link?

I'm currently writing a chat program in PHP and AJAX and have PHPMailer installed and in use.

The chat program will be available to businesses who join my site so they can live chat to their clients. I need to be able to provide clients with an easy way to start chatting with a business without having to go through the rigmarole of waiting to receive an email then clicking a link to get verified.

Currently my email checking is done first through Javascript as follows;

 // Chat Start - Validate Input Data - Chat Start Email
 $(document).on('input','#csmail',function() {
 var csmail=$("#csmail").val();
 var regex = /^([a-zA-Z0-9_\.\-\+])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
 if(!regex.test(csmail)) {
 $("#csemail").html("Email Address <span class='red'>invalid!</span>");
 } else {
 $("#csemail").html("Email Address");
 }
 });

Then a further check is done via PHP and an AJAX response is sent back after the email domain has been checked, code below is when domain validation fails;

 <?php
 // Email
 $csmail = mysqli_real_escape_string($con_usr_pub, $_POST['csmail']);
 $csmail_host = strtolower(substr(strrchr($csmail, "@"), 1));
 $csmail_host = idn_to_ascii($csmail_host.'.');
 if (filter_var($csmail, FILTER_VALIDATE_EMAIL) === false || !checkdnsrr($csmail_host, "MX")) {
 $response[] = "email";
 }
 ?>

The issue is that only the domain is being checked here and this will inevitably allow misuse of chat to occur so my question is: is there a way to use PHPMailer to contact an email address and get a result back which can be used to properly verify the full email address? Or is there any other way an email can be fully verified without relying on the user to wait for an email to be sent and them clicking on a link?

Many thanks.