Trouble with PHP sending emailing from contact form - php

Question

I have a site up and running and cant seem to get the php to send the form data. Get thank you message sometimes but never appears in mail. my aim is to have the form collect the data then email the data to the client.
Thanks for any help. I am struggling to get to grips with php it would appear.
<?php
$to = "********#*******.com";
$subject = "Contact Us";
$email = $_REQUEST['email'] ;
$message = $_REQUEST['enquiry'] ;
$headers = "From: $email";
$sent = mail($to, $subject, $message, $headers) ;
if($sent)
{print "Your mail was sent successfully";}
else
{print "We encountered anerror sending your mail";}
?>
<section class="container">
<section class="col-lg-6 col-lg-offset-1">
<form class="form-horizontal text-center" role="form" method="post" action="form_send.php">
<div class="form-group">
<label for="Name" class="col-lg-2 control-label">Name:</label>
<div class="col-lg-6">
<input type="name" class="form-control" id="name" name="name" placeholder="Enter Name...">
</div>
</div>
<div class="form-group">
<label for="Email" class="col-lg-2 control-label">Email:</label>
<div class="col-lg-6">
<input type="email" class="form-control" id="email" name="email" placeholder="Enter Email...">
</div>
</div>
<div class="form-group">
<label for="Phone" class="col-lg-2 control-label">Phone:</label>
<div class="col-lg-6">
<input type="phone" class="form-control" id="phone" placeholder="Enter Phone Number...">
</div>
</div>
<div class="form-group">
<label for="Enquiry" class="col-lg-2 control-label">Enquiry:</label>
<div class="col-lg-6">
<textarea type="enquiry" class="form-control" rows="5" id="enquiry" name="enquiry" placeholder="Enter Email..."></textarea>
</div>
</div>
<div class="form-group">
<label for="Enquiry" class="col-lg-2 control-label"></label>
<div class="col-lg-6">
<button class="btn btn-primary" type="submit">Send Message</button>
</div>
</div>
</form>
Reply from email server:
Technical details of permanent failure: Google tried to deliver your message, but it was rejected by the server for the recipient domain peoplespropertyshop.co.uk by aspmx.l.google.com. [2607:f8b0:4003:c02::1a]. The error that the other server returned was: 550-5.1.1 The email account that you tried to reach does not exist. Please try 550-5.1.1 double-checking the recipient's email address for typos or 550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1 support.google.com/mail/bin/answer.py?answer=6596 t6si822722oei.44 - gsmtp

Answer 1

First you should check that your code is in one file (form_send.php). After that add some check if user have submitted the form:
if (!empty($_POST))
Message is sent to $to email. If you want to change that, pass $email paramter to mail() function:
$sent = mail($to, $subject, $message, $headers) ;
to:
$sent = mail($email, $subject, $message, $headers);
Also check your mail server configuration and add some validation.
$email = htmlentities($_REQUEST['email']);
$message = htmlentities($_REQUEST['enquiry']);