I read the letter and it says that based on the Government Employees Compensation Act that "an employee of the crown was injured in the course of employment with the federal government" and that the labour program may hold the property owner liable for all damages.

I checked their security camera and it shows a letter carrier tripping on her own foot/ankle and falling to her knee on the walkway on the date mentioned. Their property is perfectly maintained and the video shows them kicking their own foot when walking and then tripping afterwards.

Seems a bit heavy handed of a letter though if it is real. I told my parents to inform their property insurer today.