Since the beginning of time there has been a prevalent myth in the inventor community that a device called a “Poor Man’s Patent” was away of protecting your invention in lue of actually applying for a patent from the USPTO. This is simply NOT TRUE.
The myth is – you can mail your ideas/inventions to yourself using certified mail through the US Postal System to obtain an independent date stamp on your idea and it will prove that you had the idea first and thus you are entitled to patent protection. . If done in a tamper proof envelope this could in fact establish that, on the date of the time stamp the document inside did in fact exist under government control. It would not however establish the patentability of the idea, or prove that you actually originated the idea.
Additionally, using this device can also harm you in the future, because an inventor must be diligent in pursuing an invention. If you used such a device to establish an idea date, then did no further action to formally protect the idea, it could be argued that you have not actively pursued your invention, have abandoned it, or even concealed it- all which could pose problems in the future if you attempt to obtain a valid patent.
if you use this method, then toss it into your desk drawer thinking 5 years from now you will be able to claim inventor status when you see your idea on a store shelf…..you will likely be very disappointed.