Email envelope

An email envelope is the “envelope from” address of an email message, and it’s used for routing. Every email contains two “from” addresses, “envelope from” and “header from.” The “header from” address is what people normally think of as the “from” address. It’s visible to all email users and displays in the “from” field of an email. This address is read by users and email clients but isn’t used for email delivery. The “envelope from” is a return path, which is the return address hidden in the email message header that instructs mail servers or inbox service providers (ISPs) where to return messages if they bounce. This address is used for email delivery.