Glossary
Mail transport
Return-Path
A header the receiving server writes at delivery time, recording the envelope sender it was given. It is where bounces go, and it is the best evidence of the envelope sender in a delivered message.
Defined in RFC 5321 §4.4.
Where this appears
The lessons that use this term, and what each is for.
Email Authentication FundamentalsThe two From addressesTell the envelope sender from the header From in a raw message, and say which one the recipient sees.SPF PractitionerGetting a vendor to alignConfigure a custom return-path so a platform’s mail aligns under relaxed mode.Email Security PractitionerHolding a vendor to itGet a specific alignment commitment from a sender, or establish on the record that they cannot meet it.