The Return-Path — also called the envelope sender, bounce address or MAIL FROM — is the address a mail server records as the true origin of a message and the destination for any bounce notifications. It travels in the SMTP "envelope" rather than the visible message, so it is often different from the From address a recipient sees.
How the Return-Path works
During an SMTP conversation, the sending server states the envelope sender in the MAIL FROM command; the receiving server writes it into the Return-Path header. If the message cannot be delivered, the bounce is returned to that address, which is why senders point it at a mailbox or feedback system they monitor. The Return-Path domain is also what SPF authenticates, so it must be aligned for DMARC to pass on the SPF side.
Why the Return-Path matters
A correct Return-Path is essential for bounce processing and authentication: it lets Mailpro capture and suppress failed addresses automatically and keeps SPF aligned, both of which protect sender reputation. Read everything about email bounces, see how to manage bounces, or configure your SPF record.
Mailpro and bounces
Bounces captured and handled automatically
Mailpro sets the Return-Path for you, catches every bounce and suppresses dead addresses automatically, so your list stays clean and your SPF stays aligned without manual work.