The back of a typical postcard is divided into two sections. In a properly formatted card, the recipient's address is placed in the right-hand section. The name is written first, in the middle. Underneath that is the street address. Below the street is the city, state and zip code. A stamp belongs in the upper right-hand corner. The message is written on the left side of the postcard.
The traditional format for a postcard's message is much like that of a friendly letter. To save space, it is fine to left-justify the entire card. The note starts with a familiar greeting, such as "Dear," followed by the recipient's name and a comma. A less formal greeting, such as "Hi," is also appropriate for a postcard. In that case, it is acceptable for the recipient's name to be followed by an exclamation mark.
After the greeting is the body of the letter. When this is finished, the message is ended with a closing and signature. An informal closing, such as "See you soon," followed by a comma, is suitable. The more reserved "Sincerely" or "Yours truly" is not mandatory. The sender's signature is positioned under the closing.
The body of the postcard is usually written in an informal manner. The sentences typically describe the activities in which the writer has been participating. Contractions are commonly used.