I spent so many hours reading swans documents to realise that the recovery code that will be sent to the email (that you don't have access to) is the MAC address.
This did not worked with one of the DVR's I have tested, but this gave a perfect hint on how to obtain recovery key which is surprisingly just a MAC address, so f*uck knows why but swann scanner tool did not work, I simply checked the router what devices are connected to it and picked up the device MAC address from there. Thanks from for the tip
True. Then again if the unit is not connected to internet (which is not required to operate) there's no way it's sending an email. Would have been easier if all the Swanns units had a physical reset button !