Configuring mail to use Microsoft Exchange Connector without SMTPAuth doesn't work

[Tuckbros]

I had a hard time finding out how to make it work, and still don't know why it doesn't work.
But any way, when the

Use SMTP Authentication: (Almost always, yes)

is set to

No

as per my requirements, the mail test mail is not sent and is facing an error :

SMTP Error: Could not authenticate.

as a workaround I enclosed the 3 lines of users/helpers/helpers.php involved in SMTPAuth in the following if condition

    if (strpos(strtoupper($results->useSMTPauth), "TRUE") !== false) {
        $mail->SMTPAuth = $results->useSMTPauth;                // Enable SMTP authentication
        $mail->Username = $results->email_login;                 // SMTP username
        $mail->Password = html_entity_decode($results->email_pass);    // SMTP password
    }