Just an update regarding this gateway. No issues have been found. The gateway appears to still be working fine as usual. Be sure you have configured it correctly as follows.
Response Method
Response Method: Sent to your server as a POST containing XML
Approved URL: URL as provided in gateway params
Declined URL: URL as provided in gateway params
Paypage Appearance
Buttons
Cancel Button URL: URL as provided in gateway params
Response/Receipt Data
Response/Receipt Field Configuration
Enable all checkboxes here
Asynchronous Transaction Response
Async Response URL: URL as provided in gateway params
Security Features
Transaction Verification
Enable Transaction Verification: Checked
Response Method: Displayed as XML on our server.
With the above all test purchases have been successful. If you're still having issues please contact Moneris as perhaps is an account issue. Feel free to use the below where test credentials are provided to the right of the login form in order to test.
esqa.moneris.com/mpg/index.php