I am assuming you bought one of the shim steel gaskets. If that is the case, it doesn't look like the bend is anywhere near severe enough to have killed the gasket. You're sort of stuck here: if the package was insured, the post office is going to refuse coverage on grounds of inadequate packaging (they'll say there should've been some rigid, unbendable stiffeners in the package, such as slats of wood...and they'll be right). If the package wasn't insured, they'll say "Next time buy insurance".
You haven't shown us pics of the unwrapped gasket, but from where I'm sitting it still looks fine for installation.