I purchased a Shield 9mm online from GrabaGun almost 2 weeks ago and took delivery & FFL transfer a few days later.
Questions:
1 - Looking at the online rebate application & filling it out is simple enough except the part where it says to include a pdf copy of the sales invoice. How do I do that?
2 - Is the transaction confirmation email I got from GrabaGun the document they want?
3 - If so, how do I get that to go in the "slot" on the online application?

I have printed off the purchase confirmation email and the application itself, along with the FFL's receipt. Will all that suffice if I just mail it in via the USPS?

Signed, computer illiterate old guy.