Is seller protected if he sent the item but didnt got paid by buyer.

[Riz1alam]

I put something on market place and the buyer asked me to sent an invoice on paypal, i sent them the invoice on paypal on which they said they will pay once they receive the item which i posted on recorded delivery and they received the item but still didn't paid yet.

[kernowlass]

@Riz1alam 

Why would you send something before being paid ?????