Return-Path and From are different fields and receivers read both

A message carries two identities: the From header the customer sees, and the envelope sender the receiving server uses for bounces and SPF. Aligning them badly is a common cause of mail landing in spam with no obvious error.

What each field controls

SPF checks the envelope sender, which is the domain after MAIL FROM during the SMTP conversation and shows up as Return-Path in the delivered message. DKIM signs parts of the message and is validated against the d= domain in the signature. DMARC requires that at least one of them aligns with the From header domain.

The common misconfiguration

Sending as From: [email protected] while the envelope is [email protected]. SPF passes for provider.com, DKIM may pass for provider.com, and DMARC fails because neither aligns with example.com. The fix is to sign with your own domain and use a return-path subdomain you control, or to use the provider's domain for both.

Why the bounce address matters operationally

Bounces go to the envelope sender, not to From. If the envelope is a black hole, you never learn that a mailbox is dead, and you keep sending to it. Use a real mailbox for the return-path, or one that your provider processes and reports back.

The check to run once

Send a message to a Gmail address you control, open the original, and look at Authentication-Results. Both spf and dkim should say pass, and the header should show the same domain you put in From.

Volanea sets the return-path per sending domain and reports SPF, DKIM and DMARC results together, so misalignment shows up before a customer reports it.