What Are the USPS Rules Regarding Marking Mail "return to Sender"?
Recipients are advised to mark unwanted mail as "refused" and return it unopened to the U.S. Postal Service within a reasonable amount of time. Following this procedure excuses the recipient from paying for new postage for returns. Some forms of correspondence cannot be refused after delivery, including certified, registered, insured and collect-on-delivery mail or anything requiring an adult's signature.
Recipients can refuse most mail at the time of delivery by simply choosing not to accept it from the mail carrier. The USPS recognizes that many people aren't home at the time of delivery, so recipients are granted a window of opportunity to refuse the unopened mail. Since some types of mail require signatures, receipts or acceptance in person, the recipients must cover the postage fees if they decide to send it back after accepting the initial delivery.
Individuals or businesses hosting promotions can refuse response mail during delivery but cannot return it cost-free after that point. Mail that has been opened or is excluded from postage-free refusal can be returned by placing the contents in a new envelope or package with the appropriate postage. If individuals want to automatically refuse foreign mail or block all mail from a specific sender, they must submit a written request to the USPS to withhold correspondence for up to two years.