What is the ruling on remote trade from a foreign, non-Muslim country, and what is the ruling on the dollar after it is spent in a Muslim country?

There is no objection to conducting remote trade—whether from Islamic or non-Islamic countries—if it involves permissible goods or services. This is based on Allah's saying: "And Allah has permitted trade and forbidden interest." As for the dollar or other currencies, if a Muslim acquires them through legitimate means, there is no objection to him benefiting from them. It is stipulated for currency exchange (sarf) that possession occurs in the contracting session, either actually or constructively. Examples of constructive possession include a bank transfer or handing over a certified check.