HTML5 Contact form is submitting without any data in fields - php

Question

My first time posting here so apologies if i get anything wrong. I have recently built a site from a HTML5 UP template - www.vancareleeds.co.uk. I have used the contact form that came with the template and used a simple mail.php file in the root folder to action the email to be sent to my inbox.
I have also put in Google ReCaptcha but am since struggling to force the form to validate (EG. the form can be sent without the reCaptcha being ticked and it can also be sent with no information in the fields on the form.
I have provided my code here of the .php and also the webpage itself.
If i have broken protocol or best practice for psots i apologise.
mail.php
<?php $name = $_POST['name'];
$email = $_POST['email'];
$message = $_POST['message'];
$mobile = $_POST['mobile'];
$vehicle = $_POST['category-vehicle'];
$service = $_POST['category-service'];
$formcontent="From: $name \n Message: $message \n Mobile: $mobile \n Vehicle: $vehicle \n Service Required: $service";
$recipient = "info#vancareleeds.co.uk";
$subject = "Contact Form from VanCare Website";
$mailheader = "From: $email \r\n";
mail($recipient, $subject, $formcontent, $mailheader) or die("Error!");
echo "Thank You!";
?>
form html
<form method="post" action="mail.php">
<div class="field">
<label for="name">Name</label>
<input type="text" name="name" id="name" />
</div>
<div class="field">
<label for="email">Email</label>
<input type="email" name="email" id="email" />
</div>
<div class="field">
<label for="message">Message</label>
<textarea name="message" id="message" rows="4"></textarea>
</div>
<div class="g-recaptcha" data-theme="dark" class="g-recaptcha" data-sitekey="6Lf1OVMUAAAAAJv1fNtt-CJEFPK-Q0Ugc1CVCRVh"></div><br/>
<ul class="actions">
<li><input type="submit" value="Send Message" /></li>
</ul>
</form>

Answer 1

Welcome +Catalan Soccer! I would suggest to you if you are new to PHP to use var_dump(), print_r() or var_export() the result of the $_POST global array to see what was sent to your PHP script. All other things you can comment out and uncomment if you feel confident.
$errors = [];
if ($_SERVER['REQUEST_METHOD'] === 'POST' && isset($_POST['name'], $_POST['email'], $_POST['message']) === true) {
$name = filter_var(trim($_POST['name']), FILTER_SANITIZE_STRING);
if (empty($name) === true) {
$errors['name'][] = 'Name is empty';
} elseif (ctype_alpha($name) === false) {
$errors['name'][] = 'Name contains invalid characters';
}
$email = filter_var(trim($_POST['email']), FILTER_SANITIZE_EMAIL);
if (empty($email) === true) {
$errors['email'][] = 'E-mail is empty';
} elseif ($email === false) {
$errors['email'][] = 'Invalid e-mail address';
}
$message = strip_tags(trim($_POST['message']));
if (empty($message) === true) {
$errors['message'][] = 'Message is empty';
}
if (count($errors) === 0) {
echo 'Thank you!';
// you can use here the sanitized user input to send the e-mail
}
}
if (count($errors) > 0) {
foreach ($errors as $field => $messages) {
echo implode(', ', $messages), '<br>';
}
}
This will test user input and print out error message.