We have had this plugin installed since the site was launched in 2012. There are frequent updates to the plugin and it hasn't caused any issues for us. We did modify the 'send' button to say 'contact us' instead, so every time there is an update we have to remember to edit the submit.php file in order to remove the word 'Send' from the file. Need to find a solution to this. When I find one I'll post it here.