Return-Path
also: Envelope From, Bounce Address, Reply-To Path
An email header field that specifies the address to which bounce messages and delivery failure notifications should be sent; used by mail systems to route non-delivery reports.
Return-Path is a standard email header that identifies the address responsible for receiving bounce messages and delivery status notifications. When an email cannot be delivered to a recipient, the mail server uses the Return-Path address to send back an error report (called a bounce or Non-Delivery Report).
This is distinct from the From: header, which is what users see as the sender. The Return-Path is typically set automatically by the mail transfer agent (MTA) and is often the same as the sender's address, but can be configured differently—for example, to send bounces to a separate monitoring address.
Example: An email sent from [email protected] might have Return-Path: <[email protected]> or Return-Path: <[email protected]> if the organization wants to centralize bounce handling. If delivery fails, the bounce message goes to whichever address is in Return-Path.