On Thu, 2021-05-20 at 16:12 -0400, Alex wrote: > > X-Envelope-From: > <bounces+3940809-b10a-43194=hotel.example....@em8909.cookspest.com> > > > Perhaps it's because Return-Path is null? > Return-Path: <>
Return-Path is supposed to be where your MTA stores the envelope sender. That it doesn't match is probably a problem. And yes, SPF falls back to testing the HELO host if the envelope sender is empty (which should only occur in bounces or auto-responses).
