Can you tell me the differences between a letter and a memorandum , Miss Thong ?   Certainly . A letter must be sent out of the company and must be mailed or posted . A memorandum is a communication within an organization .   Should we use the layout we use for a letter when we write a memorandum ?   No , not necessary . Usually we have a set form which is printed . We just fill in the printed forms and send it to the person or the offices concerned in the company .   Of course , let me find one for you . 