php email sent successfully but not received by gmail

php email sent successfully but not received by gmail

I have some code that has worked for me in the past, but isn't anymore,
for some reason I don't understand. I'm pretty sure the problem isn't in
the code itself, since 1) I haven't changed anything, and 2) it's worked
for me in the past. I am using XAMPP and PHP. My webpage allows a user to
fill out a contact form and send an email through PHP. It seems to execute
successfully, since it takes the user to thankyou.html as a result. To
troubleshoot the issue, I have 1) cleared my browser's cache and 2)
checked my spam folder in Gmail. But I still can't find my email, and
don't know why. I'm not familiar with how SNMP works, so if that may be
the issue, I could use an explanation. Here is the code:
<?php
$field_first_name = $_POST['cf_first_name'];
$field_last_name = $_POST['cf_last_name'];
$field_email = $_POST['cf_email'];
$field_message = $_POST['cf_message'];
$field_reference = $_POST['cf_reference'];
$mail_to = 'myself@gmail.com';
$subject = 'Message from a website visitor '.$field_first_name.'
'.$field_last_name;
$body_message = 'From: '.$field_first_name."\n";
$body_message .= 'E-mail: '.$field_email."\n";
$body_message .= 'Message: '.$field_message."\n";
$body_message .= 'Reference: '.$field_reference;
$headers = 'From: '.$field_email."\r\n";
$headers .= 'Reply-To: '.$field_email."\r\n";
$mail_status = mail($mail_to, $subject, $body_message, $headers);
if ($mail_status) { ?>
<script language="javascript" type="text/javascript">
//alert('Thank you for the message. We will contact you
shortly.');
window.location = 'thankyou.html';
</script>
<?php
}
else { ?>
<script language="javascript" type="text/javascript">
alert('Message failed. Please, send an email to
someemail@gmail.com');
window.location = 'home.php';
</script>
<?php
}
?>
Any input is much appreciated!