False Inauthentic Claim on Nike Shoes

just received an email stating that a customer claimed a pair of shoes were inauthentic (they’re not) i got them at an outlet store. I did use a different box so maybe that’s why they made the complaint. Luckily I sold all of them so I don’t have to worry about having anything stranded but i’m wondering if a picture of the recipient from nike will be enough to verify the authenticity. thanks a bunch