Traders are better off NOT using documents like LOI, ICPO, FCO, etc. Even if and when they rarely are used in internal trades, on a restricted level within specific industries, they have no legal or customary basis in International Trade whatsoever. In fact the presence of many of these terms are considered to be signs of Advance Fee Fraud, by knowledgeable players and law enforcement.
At the end you should sign off with "sincerely yours" or any other related salutation. If you are applying for a particular job then you need to create letter of intent that contains the following. First of all mention your name, address and contact number.