On Fri, Feb 16, 2007 at 08:31:15AM +0100, Jean-Pierre Schwickerath wrote:
- Serious design flaws (such as the forwarding problem).
SPF is there to prevent mail with your sender envelope address to be relayed/forwarded by mailservers that are not meant to use your address. When you forward a mail in your MUA, you don't use the original sender in the From: header, do you? When a mailserver is relaying mail it is supposed to use its own sender envelope address. One possibility for that is SRS.
All mailing list forward mail with the original sender in the enveloppe and if you forward your mail on one server to another one with e.g. a simple .forward rule it will also re-use the same envelope from address. Forwarding mail is very common and it is important to use the same envelope form address in the forwarding path. Everybody who denies this fact does not understand the email system and the way bounces work.