Mailgun PHP integration not working with form submissions

Other Questions Mailgun
1

I’m having trouble getting Mailgun to work with my contact forms in PHP. The weird thing is that when I test Mailgun by itself, emails go through just fine. But when I try to use it with my actual forms, nothing gets sent.

require 'vendor/autoload.php';
use Mailgun\Mailgun;

if($_GET['action'] == 'contact_form'){
    $recipient = '[email protected]';
    $body = 'Full Name: '.$_POST['fullname'].'<br />';
    $body .= 'Phone: '.$_POST['phone'].'<br />';
    $body .= 'Email Address: '.$_POST['email_addr'].'<br />';
    $sender = $_POST['fullname'].' <'.$_POST['email_addr'].'>';
    $username = $_POST['fullname'];
    
    $email_subject = 'New Contact Form Submission';
    
    $mail_headers = "MIME-Version: 1.0" . "\r\n";
    $mail_headers .= "Content-type:text/html;charset=iso-8859-1" . "\r\n";
    $mail_headers .= 'From: '.$username.' <'.$_POST['email_addr'].'>' . "\r\n";
    
    dispatch_email($recipient, $sender, $email_subject, $body);
}

else if($_GET['action'] == 'quote_form'){
    $recipient = '[email protected]';
    $body = 'Customer Name: '.$_POST['customer_name'].'<br />';
    $body .= 'Phone Number: '.$_POST['phone_num'].'<br />';
    $body .= 'Email: '.$_POST['user_email'].'<br />';
    $sender = $_POST['customer_name'].' <'.$_POST['user_email'].'>';
    $customer = $_POST['customer_name'];
    
    $email_subject = 'Quote Request Received';
    
    $mail_headers = "MIME-Version: 1.0" . "\r\n";
    $mail_headers .= "Content-type:text/html;charset=iso-8859-1" . "\r\n";
    $mail_headers .= 'From: '.$customer.' <'.$_POST['user_email'].'>' . "\r\n";
    
    dispatch_email($recipient, $sender, $email_subject, $body);
}

function dispatch_email($recipient, $sender, $email_subject, $message_body)
{
    $mailgun = new Mailgun('my-mailgun-api-key');
    $mail_domain = "mail.mywebsite.com";
    
    $response = $mailgun->sendMessage($mail_domain, array(
        'from' => $sender,
        'to' => $recipient,
        'subject' => $email_subject,
        'text' => $message_body
    ));
}

I think the problem might be with the ‘from’ parameter because when I hardcode a static email address instead of using the variable, the emails actually get delivered. Anyone know what could be causing this?

2

yeah, it’s probly the sender verification issue. mailgun wants emails from verified domains only - using personal emails won’t work. try setting the ‘from’ to ‘[email protected]’ and just use the user email in the ‘reply-to’ header. fixed it for me.

3

Yeah, it’s definitely the sender domain authentication. Mailgun won’t let you use random email addresses from form submissions as the ‘from’ address - they need to be from a domain you’ve verified with proper SPF/DKIM records. I hit this exact same wall last year and wasted hours on it. Here’s what fixed it: use a static from address like ‘[email protected]’ and stick the original sender’s email in a ‘Reply-To’ header instead. Also noticed you’re setting those mail_headers variables but not using them in your sendMessage call - might want to clean that up too.

4

This is a domain authentication issue with Mailgun. They reject emails when you use form submission addresses directly in the ‘from’ field because those addresses aren’t verified through your DNS records. I hit this exact problem six months ago and wasted hours debugging it. Here’s the fix: use a verified sender address from your authorized domain for ‘from’, then put the original submitter’s email in ‘reply-to’. Also, you’re building those mail_headers but not passing them to sendMessage, so they’re doing nothing. Just add a ‘reply-to’ parameter to your sendMessage array instead.