So, yeah except the Vendor is being completely annoying, they should accept the receipt as valid for two reasons.

1. The person can send it to them in any format, so they can examine it to see if it’s real or not.

2. It carries the date and other details that they can use to cross reference with their own records.

And finally, this question actually reminds me of a feature I considered earlier:

- Adding a logo embed feature so the document can be more recognizable.

But it didn’t come up as necessary during research, so we'll see how it goes in further iterations.