If you receive this message:
[Your Store] has been turned off. This is because your Volusion store is not on a high enough plan, it needs to be hosted on a Plus or higher plan. You'll need to upgrade your plan for Autoresponder Max to work correctly. If you are still experiencing issues, please contact support. 
This error sometimes may safely be ignored, as at times Volusion will provide false information on level plan your store is currently on. If this issue continues to occur, the issue may actually be the plan of your Volusion store is not high enough. The recommendation would be to try turning back on your store and if you still receive this error message to contact support.