Sender Policy Framework

Rewriting the From header

One objection about SPF lite authentication is that the sender address is only seen in the Return-Path if a user cares to display the message source. Normally, only the text of the From header is visible. Therefore, it makes sense to rewrite the From header in case its domain part differs from the one in Return-Path. For example, in a message having

Return-Path: <bounces@lists.example.net>

...

From: A User <user@example.com>

the last line should be rewritten as, e.g,

From: lists.example.net FOR A User <user@example.com>

That helps the end users discriminating human to human (H2H) messages vs bots. It can be applied independently of SPF.

That rewriting should be skipped for messages delivered to mailing list-specific subfolders of imap mailboxes.

Spam comes in both h2h and bot styles.