In one typical use of freepost, a business sends bulk mail to potential customers, the bulk mail including envelopes or postcards that potential customers can return to the business by freepost. In another typical use, magazines include subscription cards that potential subscribers can return by freepost. In yet another typical use, a seller can provide a merchandise return label bearing the appropriate freepost indicia (as described below) to a customer so that the customer can return the item to the seller by freepost upon issuance of a Return Merchandise Authorization.
In Australia, freepost is called Reply Paid. Specially printed envelopes are used, with the permit holder's address, the words "Reply Paid" with an authorization number. The stamp is replaced by three black stripes. The permit holder pays the postage plus a fee to the postal authority. The customer may write the Reply Paid envelope out by hand.
More recently, the post office has realised that it can combine the RP number and the Box number, which saves writing and reduces the number of errors.
An important customer like the Taxation Office would have an RP number the same as the post code, to minimize errors even more.
In the United States, the United States Postal Service refers to freepost as business reply mail. A mailer wishing to receive mail by freepost must obtain a business reply permit and design the envelopes, postcards, or labels according to the standards specified by the USPS, including the use of a FIM B or C code, whichever of the two is appropriate. The address on the envelope, postcard, or label is the same as the address for regular mail, except that the ZIP+4 code is different. In some large cities, business reply mail has its own five-digit ZIP code or codes (e.g., 20077 and 20078 in Washington, D.C.). Also, the design of the envelope or postcard includes a place to identify the business reply permit number.
Other countries use freepost as well, although the envelope designs required by those countries' postal authorities differ widely from that described above. A freepost address may have a special freepost number for use along with, or instead of, the address for regular mail.
International freepost also exists and is known variously as "International Business Reply Service," "International Business Reply Mail" and "Réponse Payée." Like USPS business reply mail, international business reply mail must conform to certain format requirements.