returnaddress

Return address is a term used in different domains to denote the destination to which a response or return should be directed. In postal practice, the return address is the sender’s address placed on an item of mail or a package. It typically includes a name and street address, city, postal/ZIP code, and country. The information helps postal authorities route undeliverable mail back to the sender and can facilitate processing of returns, refunds, or customs for international shipments. Providing a return address is common and, in some jurisdictions, required for outbound mail.

In electronic mail, the concept is related but technically distinct. The Return-Path header (set by mail servers) indicates the bounce address used for non-delivery notifications; the From header identifies the author-facing address, while the Reply-To header may specify a preferred address for replies. Some interfaces label the return address as the address to which replies should be sent, but it does not always reflect the actual path used for delivery confirmations.

In computing, the return address is the location in memory to which execution returns after a subroutine or function call. When a function is invoked, the processor saves the return address on the call stack; upon completion, control transfers back to that address. The return address concept is central to stack frames, program flow, and related security considerations, such as protections against return-oriented attacks.

Overall, the return address serves as a means to route responses or restore control flow, depending on whether the context is physical mail, electronic messaging, or software execution.