It is customary to write Congratulations Letters to our relatives, close friends, colleagues and business associates on events such as birth, marriage, graduation from school/college, securing a job/promotion, success of business venture etc to show feelings of friendship, affection and happiness in the well being and prosperity of the recipient.
One should not write Congratulatory Letters to total strangers. Congratulation letters must be warm, sincere and convey genuine feelings of happiness. They should hope for providential blessings for the grant of many more such happy events in the future. The letter should mention the full address of the sender to enable the recipient to send a ‘Thank You’, if he so desires.