Postage can be affixed in 1 of 3 ways for most classes of mail: using postage stamps, using a postage meter, or printing a postal permit indicia on the mail piece.
Stamps: Using postage stamps generally creates a more personalized look to the outside of your mail piece and is often used on envelopes. The more personalized your mail piece looks, the better your response rate will be.
Meter: Affixing postage with a postage meter is commonly used for statement or invoice mailings that are mailed in an envelope. (Using metered mail can also make sense for a Business-to-Business direct mail campaign — as most businesses meter their daily out-going mail.)
Permit/Indicia: Using a pre-printed postal indicia is generally used on self-mailers, such as postcards, newsletters, and catalogs — and can also be used on envelope mailings of at least 200 pieces. Using indicias is generally the least expensive way to affix postage to your mail piece.