What is the safest and cheapest legal way to send money to Bangladesh from Kuwait?

Use a licensed exchange house or a bank, never hundi. Licensed exchange houses in Kuwait are regulated by the Central Bank of Kuwait and give you a receipt and a tracking number. Hundi is illegal, gives no receipt, and you can lose everything if it goes wrong. When you send through a legal channel, your family in Bangladesh can also receive the government's 2.5% cash incentive on the amount. To send, bring your Civil ID. Compare the rate and fee at a few exchange houses, because they differ. Keep every receipt. Sending legally protects your money and builds a record of your income, which helps with things like your driving licence salary check.