They told me that without the change, accepting payments would no longer be possible and that I needed to talk to my "shopping cart vendor." Now, phone support is often wrong but this is what Authorize.net told me. Then, two days ago, I got this in the mail: JUNE 30TH MIGRATION TO AKAMAI IS NOW VOLUNTARY, BUT REMAINS HIGHLY RECOMMENDED. So, they were requiring it then backed off.

As communicated over the past nine months, Akamai SureRoute technology has been introduced into our network environment as a new connection option. This technology automatically routes your transaction requests around issues that may occur on the Internet, thus helping to ensure your transactions are received by Authorize.Net, quickly, securely and reliably. Many Authorize.Net customers have already adopted this connection option and are taking advantage of the benefits offered by Akamai SureRoute technology. If you are not yet connecting to Authorize.Net via Akamai, we encourage you to do so.

WHILE WE CONTINUE TO ENCOURAGE ALL CUSTOMERS TO USE AKAMAI SUREROUTE, THE MIGRATION IS NO LONGER MANDATORY BY JUNE 30, 2016.