Imperian has hundreds of help files to help you learn more about the game and how to play.
3.11 The postal system
Each of the cities in Imperian has a post office, often located near the bank. While in a post office, the following things can be done: REQUEST LETTER: This will request a letter from the postal staff. The letters are able to not only be written on, but are able to hold things improbably large in them. The letters cost 100 gold each, and will decay within a handful of Imperian months. If you want to include items, just PUT <item> IN LETTER before you mail it. You must request a letter while in a postal office. WRITE <LETTER> [IN <language>]: Compose a letter. A letter can hold a maximum of about 100 lines. The language type will default to Common if not specified. MAIL <LETTER> TO <whomever>: Address and mail a letter to whomever it is for. You must do this in a postal office. PRESERVE <LETTER>: Sometimes, you may receive a letter you wish to keep permanently, out of sentiment, or perhaps as proof of some nefarious plot. Doing this will cost 2000 gold. You must do this in a postal office. CHAR <LETTER>: Provided you have a source of fire with you, such as a tinderbox, you can partially char a non-preserved letter, which will cause bits and pieces of it to become unreadable. This can be done multiple times. COPY <letter>: The post office offers scribe services to the general public. Taking a letter that has been written upon the post office will copy the text onto a new letter, essentially duplicating it perfectly. There is a fee associated with this serivce.