Post #2498187

It's not his SPF record. The forwarding he's talking about isn't the same as you hitting forward in your mail client. SPF only authenticates the first hop from the origin MTA. If you put a relay server in then you either need to disable SPF checking on subsequent MTAs or implement RFC8617. If you don't then when subsequent MTAs check *the original sender's SPF* it will fail because the message came from your relay.