If you use Opencart and move your shop over to use a secure certificate you might find the contact form stops sending. This appears to be a bug with the contact form in Opencart using the http version of the URL rather than the https version as the form action. To fix this try the following:

Update line 80 of public_html/catalog/controller/information/contact.php from:

$data['action'] = $this->url->link('information/contact');


$data['action'] = $this->url->link('information/contact', '', true);

Easy peasy when you know how 🙂