At the end of April (planned for 2021-04-29) we will make the following change to the -Notify (notification from  to the merchant system):

We are currently sending the value "CompuTop PayGate" in the "Referer" field in the HTTP header of the Notifies. However, the "Referer" field may only contain a URL if it is set - not any text. Since a notify is not a forwarding message, we will remove this field from the HTTP header.

This change does not require any change on your side - exept if you check the "Referer" field in your merchant system (which should not be the case), adjust your systems accordingly and also allow a notify without the "Referer" field.