Hello,
I have seen the topic from June 2016 where it was stated that Authorize.NET would be turning off GET requests for their API. Someone responded that they would update the plugin to use POST requests, but when examining the code this still has not been done.

/********************************
now lets send the whole shebang to the gateway
*********************************/
header('location: '.$gatewayUrl.'?'.http_build_query($toGateway,'','&').$x_line_item.$x_rename.'');
exit();

I have received the following email:

We previously alerted you that we will no longer be allowing HTTP GET methods for transaction requests, because HTTP GET methods do not adhere to current PCI DSS protection requirements.

We will disable HTTP GET in our production environment on May 31, 2017.

We have disabled the sandbox already to allow you and your developer time to test your website or payment solution and ensure you are no longer submitting HTTP GET requests prior to May 31st.

Please contact your web developer or solution provider for assistance, or check out our Certified Developer Directory<http://www.authorize.net/cdd&gt; to find a developer to help you.

If you have any questions about this email, please review this article<https://support.authorize.net/authkb/index?page=content&id=A1702&gt; in the Support Center or contact Customer Support.

Thank you for your attention to this matter and for being an Authorize.Net merchant.

It seems like this is not the first time they have stated this as well. It seems very strange that they would not allow simple redirects to their service. Can the plugin please be updated to meet Authorize.NET standards? It advertises that it integrates with this service.