[mailop] Carrierzone - Incorrectly Rewriting From and Return-Path Headers?

Hi -- We are seeing some odd behavior with emails delivered to recipient mailboxes protected by Carrierzone (https://carrierzone.com/). Emails leaving our platform have a proper From header. However, when they are received by Carrierzone, both the From and Return-Path headers have had the domain

Re: [mailop] Carrierzone - Incorrectly Rewriting From and Return-Path Headers?

Hi On Thu, May 27, 2021 at 02:33:10PM -0500, Chris Adams via mailop wrote: > Emails leaving our platform have a proper From header. However, when they > are received by Carrierzone, both the From and Return-Path headers have had > the domain replaced with "sparkpostmail.com". It's almost as if