improve html/php email form on my website (not built in wordpress)

Please don't try to contact me outside of freelancer. I have a website with a contact form built in html and php. Sometimes there are huge delays on when i receive the emails posted through the contact form. I would like to know: 1. is there a html/php email form solution that is reliable and will always send without delay? I have attached the code i am currently using: <?php $name = $_POST["name"]; $subject = $_POST['subject']; $email = $_POST["email"]; $phone = $_POST["phone"]; $message = $_POST["message"]; $email_from = "xxxxxxx"; $email_subject = "xxxxxxx"; $email_body = "You have received a quote request from the user: <br /> <br /> ". $name. "<br />". $email. "<br />". $phone. "<br />" .$message; $to = "xxxxxxxxxxxxxx"; $email_from = "xxxxxxxxxxxx"; $headers = "MIME-Version: 1.0" . "\r\n"; $headers .= "Content-type:text/html;charset=UTF-8" . "\r\n"; $headers .= 'From: xxxxxxxxxxxxx' . "\r\n"; //Send the email! mail($to,$email_subject,$email_body,$headers); //done. redirect to thank-you page. header('Location: [login to view URL]');