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 replaced with "sparkpostmail.com". It's almost as if they are using the organizational domain from our connecting IP's rDNS lookup and rewriting the header using that domain. A subset of the headers are below Below you can see in the Authentication-Results-Original header that the header.d is correct. But the From address has been replaced. The same thing happens with the Return-Path header. We have further verified that when the mail left our platform the headers were correct. I am curious if anybody has seen this with them or other filter providers before? And would anybody have a contact at Carrierzone that I could reach out to? Thank You! ---------- Received-SPF: SoftFail (protection.outlook.com: domain of transitioning sparkpostmail.com discourages use of 66.175.45.214 as permitted sender) Received: from mail314c28.carrierzone.com (66.175.45.214) by DB5EUR01FT007.mail.protection.outlook.com <http://db5eur01ft007.mail.protection.outlook.com/> (10.152.4.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4129.25 via Frontend Transport; Sat, 22 May 2021 14:39:08 +0000 Authentication-Results-Original: mail314c28.carrierzone.com; dkim=pass (1024-bit key) header.d=send.o*******l.com <http://send.osdealerfuel.com/> [email protected]***********l.com <[email protected]> header.b="tBmppuh8" Received: from mta-88-193.sparkpostmail.com (mta-88-193.sparkpostmail.com [192.174.88.193]) by mail314c28.carrierzone.com (8.14.9/8.13.1) with ESMTP id 14MEd3NK026470 Reply-To: "O*******d" <O*******d@o********l.com <[email protected]>> From: "O*******d" <O********[email protected] <[email protected]>> Date: Sat, 22 May 2021 14:39:02 +0000 List-Unsubscribe: <mailto:[email protected]?subject=> List-Id: <spc.278042.497.sparkpostmail.com>
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