wp_mail() function doesn’t send email in Ajax mode

When I use the wp_mail() or mail() function in AJAX, the function doesn’t work and doesn’t send email.

When I use these functions simply in my functions.php file it works fine.

It’s not related to WordPress functions or actions. I have checked everything, including using SMTP mail. SMTP mail works same as mail() function and it doesn’t send in AJAX mode.

This is my functions.php file content:

add_action( 'phpmailer_init', 'wpse8170_phpmailer_init' );
function wpse8170_phpmailer_init( PHPMailer $phpmailer ) {
    $phpmailer->Host = 'godadysmtpsampledomain.secureserver.net';
    $phpmailer->Port = 465; // could be different
    $phpmailer->Username = 'sender@mysite.com'; // if required
    $phpmailer->Password = '12345'; // if required
    $phpmailer->SMTPAuth = true; // if required
    $phpmailer->SMTPSecure = 'ssl'; // enable if required, 'tls' is another possible value

    $phpmailer->IsSMTP();

}
// This code works fine;
wp_mail("hossein@mydomain.net", "test", "test");

But other codes or plugin in AJAX mode like Contact Form 7 don’t work, it means the email doesn’t delivered. I checked these plugins and wp_mail() returns true but the email doesn’t delivered.