linguistic:paraphrasing
Letters

Letter-sized mail constitutes the bulk of the contents sent through most postal services. These are usually documents printed on A4 (210×297 mm), Letter-sized (8.5×11 inches), or smaller paper and placed in envelopes.

Handwritten correspondence, while once a major means of communications between distant people, is now used less frequently due to the advent of more immediate forms of communication, such as the telephone or email. Traditional letters, however, are often considered to hark back to a "simpler time" and are still used when someone wishes to be deliberate and thoughtful about their communication. An example would be a letter of sympathy to a bereaved person.

Bills and invoices are often sent through the mail, like regular billing correspondence from utility companies and other service providers. These letters often contain a self-addressed envelope that allows the receiver to remit payment back to the company easily. While still very common, many people now opt to use online bill payment services, which eliminate the need to receive bills through the mail. Paperwork for the confirmation of large financial transactions is often sent through the mail. Many tax documents are as well.

New credit cards and their corresponding personal identification numbers are sent to their owners through the mail. The card and number are usually mailed separately several days or weeks apart for security reasons.

Bulk mail is mail that is prepared for bulk mailing, often by presorting, and processing at reduced rates. It is often used in direct marketing and other advertising mail, although it has other uses as well. The senders of these messages sometimes purchase lists of addresses (which are sometimes targeted towards certain demographics) and then send letters advertising their product or service to all recipients. Other times, commercial solicitations are sent by local companies advertising local products, like a restaurant delivery service advertising to their delivery area or a retail store sending their weekly advertising circular to a general area. Bulk mail is also often sent to companies' existing subscriber bases, advertising new products or services.