Never pay down a deposit in a bank account until you have met the seller, seen signed a purchase agreement.
No serious private advertisers ask for a down payment before you meet.
Receiving an email with an in-scanned ID does not mean that you have identified the sender. You do this on the spot, when you sign a purchase agreement.
Dell E5520 core i.5 8gb / 500gb 15.6 inch screen num pad window 10 hdmi/camera/wifi original charger free delivery all over uae offer price just 300 aed only available in quantity