I shipped a $300 package last month to a customer via UPS.

Customer claims to not have received it.

UPS tracking says delivered on doorstep with a photo.

I’ve opened a claim with UPS and it says under investigation. Tracking now says “open investigation.”

Customer is saying she’s going to sue me and file a chargeback unless I refund her. I responded that I am waiting until UPS has completed their claim to get the insurance to refund her.

She says that she cannot wait and will just have to sue me since she thinks I’m negligent in this case.

I have copy of shipping label and screenshots of full tracking. I even take photos of the packages before I ship.

Can she actually sue me? Nothing online says she can but I’m a bit confused. What can I do in this situation to protect myself from this happening again aside from shipping insurance?