I was curious if someone purchased an item but when the item was delivered no payment was received, is this illegal?

Thanks for opening my question, I'm curious because I used an app called letgo and sold an iPhone 7 plus for $300. I agreed with the buyer if he showed proof of sending money via moneygram he agreed he would tell me the reference number after it delivered to him. Well it delivered and I have no contact. I have his address, if I report this too the police will they prosecute it?

That whole thing is a scam. You will get nothing.

You have been scammed. Police won't prosecute, this is up to you to pursue through small claims court. Why would you deliver an item before you got the money? Next time, use a mortgage account such as Paypal.

It doesn't sound good. As somebody else has said you should have required payment by PayPal (including PayPal e-check if the don't have a PayPal account) and you should certainly not have sent the item before receiving payment. Try writing to them initially using a confirmed delivery service and giving them a short deadline to respond.

No the police won't get involved because this is a civil not criminal issue. You can always sue.

No they won't, it is a civil matter because you were dumb enough to agree to send it before you received payment.

No the police do not deal with civil cases, you will have to sue him in court