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Maybe the letter is somehow related to the FBI intelligence document on Bitcoin as a collaboration with an ongoing Thai investigation and you stumbled upon the pillow of evidence. Or maybe not :)

Everywhere I go there just seems to be documents! Ha ha! #documenthunter :)

As you hunt, so you shall find!

[Applies document-repellent before leaving home!] :)

Let us know how it works out :)

Having a paper-free day so far :) Ha ha!

Watch out for any phantom pdf's out in cyber space too.