I received a package at my PO Box from a very reliable vendor but they forgot to put postage on it so I had to eat the cost of overnight shipping. The vendor is asking me for a copy of a receipt to prove I had to pay for the postage. What is the safest way to send him a picture of said receipt and the slip they put in my box that required a signature for the package because of the no postage?
exif data is of secondary importance, the thing has your fucking address on it and should not be uploaded anywhere unencrypted. Anonymous picture upload sites aren't anonymous, they're public.
Scan the receipt and email using thunderbird and enigmail plugin, encrypt to the vendor's PGP key. They can decrypt the attachment like they would decrypt your address.
If you don't have email set up you can do it from the command line in tails:
You'll then have a file called
private.jpg.asc
that you can send via messenger, upload to pastebin or whatever.