Pre-adhesive mail, also called pre-stamp mail, are letters

Mail

Mail, or post, is a system for transporting letters and other tangible objects: written documents, typically enclosed in envelopes, and also small packages are delivered to destinations around the world. Anything sent through the postal system is called mail or post.In principle, a postal service...

 carried in mail systems before the issuance of postage stamp

Postage stamp

A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are made from special paper, with a national designation and denomination on the face, and a gum adhesive on the reverse side...

s. A stampless cover is another description and generally also refers to any item of mail sent before the issuance of postage stamp

Postage stamp

A postage stamp is a small piece of paper that is purchased and displayed on an item of mail as evidence of payment of postage. Typically, stamps are made from special paper, with a national designation and denomination on the face, and a gum adhesive on the reverse side...

s but it can also refer to mail sent, after the introduction of postage stamps, unpaid (as was permitted in many countries) or without the pre-payment being indicated by the affixing of a postage stamp; it could have been pre-paid in cash and marked paid.

This mail is usually a letter sheet

Letter sheet

In philatelic terminology a Letter sheet, often written lettersheet, is nowadays an item of postal stationery issued by a postal authority. It is a sheet of paper that can be folded, usually sealed , and mailed without the use of an envelope...

 because the use of envelope

Envelope

An envelope is a common packaging item, usually made of thin flat material. It is designed to contain a flat object, such as a letter or card....

s was not popularised until after the introduction of postage stamps. Pre-adhesive mail includes court and government letters and items from the general populace before official public mail services were introduced. The mail often bears distinctive town and other marks applied worldwide.

In the United Kingdom of Great Britain and Ireland

United Kingdom of Great Britain and Ireland

The United Kingdom of Great Britain and Ireland was the formal name of the United Kingdom during the period when what is now the Republic of Ireland formed a part of it....

 pre-adhesive mail was the norm before the Penny Black

Penny Black

The Penny Black was the world's first adhesive postage stamp used in a public postal system. It was issued in Britain on 1 May 1840, for official use from 6 May of that year....

 and Two pence Blue

Two pence blue

The Two Penny Blue was the world’s second official postage stamp, issued after the Penny Black.It was issued in the United Kingdom of Great Britain and Ireland and was first sold to the public at the London Inland revenue office in the afternoon of May 8th 1840. Except for its denomination of the...

 stamps were issued by the General Post Office on 6 May 1840, and in other countries, to mail used prior to each country's postal administration adopted adhesive labels to indicate postage had been pre-paid.

In the United States, the majority of stampless mail was sent collect. This meant that the recipient of the letter paid the postage. This type of letter was not marked Paid. Pre-payment of postage was not mandatory in the U.S.A. until 1856. This greatly impacted small town postmasters as they were compensated based on the amount of postage they collected.