Sample Function To Send WP Mail

send-mail.php

<?php
function send_email() {
    $site_name = 'Company Name';
    $site_email = 'example@mail.com';
    $to = "$site_name <$site_email>";

    $name = $_POST['name'];
    $email = $_POST['email'];
    $subject = "$site_name - " . $_POST['subject'];
    $message = $_POST['message'];

    $body = "
    <p><b>Name:</b><br>$name</p>
    <p><b>Email:</b><br>$email</p>
    <p><b>Message:</b><br>$message</p>";

    $headers = "From: $site_name <$site_email>\r\n";
    $headers .= "Reply-To: $name <$email>\r\n";
    $headers .= "Content-Type: text/html; charset=UTF-8";

    return mail( $to, $subject, $body, $headers );
}

if ( !empty($_POST) ) {
    $mail = send_email();
    $message = $mail ?
        '<b>Thank you</b><br>Your message has been sent successfully!' :
        '<b>Sorry</b><br>There was an error sending the message. Please try again.';
    echo json_encode( array(
        'success' => $mail,
        'message' => $message
    ));
}
?>