Gmail shows “via” even if the domain is authenticated with Mailchimp and has valid SPF and DKIM records

Question

I'm sending a newsletter with Mailchimp and Gmail shows that the mail is sent via mail5.mcsignup.com even though I added Mailchimp's SPF and DKIM records and the domain is authenticated in Mailchimp.

Outlook also shows that the email is sent "on behalf of".

I have tested the SPF with mxtoolbox.com and the DKIM with dkimcore.org and they are valid.

It also looks that the SPF and DKIM pass in the gmail header. Below is the header from Gmail:

   *ARC-Authentication-Results: i=1; mx.google.com;
           dkim=pass [email protected] header.b=G93ARUrl;
           dkim=pass [email protected] header.b=i0uux1aP;
          spf=pass (google.com: domain of bounce-md_9656357.596bc38e.v1-
    [email protected] designates 205.201.136.19 as 
    permitted sender) smtp.mailfrom=bounce-md_9656357.596bc38e.v1-
    [email protected]
    Return-Path: <bounce-md_9656357.596bc38e.v1-
    [email protected]>
    Received: from mail5.mcsignup.com (mail5.mcsignup.com. [205.201.136.19])
            by mx.google.com with ESMTPS id 
   d10si3015324yba.575.2017.07.16.12.50.38
            for <[email protected]>
            (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
           Sun, 16 Jul 2017 12:50:38 -0700 (PDT)
    Received-SPF: pass (google.com: domain of bounce-md_9656357.596bc38e.v1-
    [email protected] designates 205.201.136.19 as 
    permitted sender) client-ip=205.201.136.19;
    Authentication-Results: mx.google.com;
           dkim=pass [email protected] header.b=G93ARUrl;
           dkim=pass [email protected] header.b=i0uux1aP;
           spf=pass (google.com: domain of bounce-md_9656357.596bc38e.v1-
    [email protected] designates 205.201.136.19 as 
    permitted sender) smtp.mailfrom=bounce-md_9656357.596bc38e.v1-        
    [email protected]
    DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; s=mandrill; 
    d=mail5.mcsignup.com; h=From:Sender:Subject:To:Message-Id:Date:MIME-
    Version:Content-Type; [email protected]; 
    bh=fnyV42cJxlWmSMb63R6R/rVuLTzDaUFDaGqL0N4WaMA=; 
   b=G93ARUrloP6yy40uMAHkv9TNXH/7GDjg4ozK0rk7oeKQ40lWaWzkB8UTgsMyHTSNLNneWdcTWlCO       
     INNBCc55gqlISw08WRn52e+7gQWx8vllJv77RiJiX58wFJYsTbrLQA086QQ/8EYEKo9Mtgqzxg4/
       2CFWJPCv3XKRgg6Nnmg=
    Received: from pmta07.mandrill.prod.suw01.rsglab.com (127.0.0.1) by 
    mail5.mcsignup.com id hdf1os174e0q for <[email protected]>; Sun, 16 Jul 2017 
    19:50:38 +0000 (envelope-from <bounce-md_9656357.596bc38e.v1-
    [email protected]>)
    DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mandrillapp.com;
      [email protected]; q=dns/txt; s=mandrill; t=1500234638; h=From :
      Sender : Subject : To : Message-Id : Date : MIME-Version : Content-Type
      : From : Subject : Date : X-Mandrill-User : List-Unsubscribe;
      bh=fnyV42cJxlWmSMb63R6R/rVuLTzDaUFDaGqL0N4WaMA=;
      b=i0uux1aPb7yxSqpYdr5e45hKJHeAb1ow5k4xE9K7/NxlKt4JW9xvSS3AazIojjleDpLqfC 
    4gESZATfoj6eAXRSqoq2+o6Jxfwi7tvEdTf4IjdonTl3QioXSHJj/joagC8nKJ3HQIaPIh+I 
    xycoNL7i/nXzcQqlslsYW9z1G+/Hs=
    From: MY COMPANY <[email protected]>
    Sender: MY COMPANY <[email protected]>
    Subject: MY SUBJECT
    Return-Path: <bounce-md_9656357.596bc38e.v1-
    [email protected]>
    X-Accounttype: ff
    X-Auto-Response-Suppress: OOF, AutoReply
    Auto-Submitted: auto-generated
    Form-Sub: v=1;ip4=MY IP
    To: "[email protected]" <[email protected]>
    X-Report-Abuse: Please forward a copy of this message, including all headers, 
    to [email protected]
    X-Report-Abuse: You can also report abuse here: 
     http://mandrillapp.com/contact/abuse?
    id=9656357.43028f7e330f4128b36015188bc1fb10
    X-Mandrill-User: md_9656357
    Message-Id: 
    <9656357.20170716195038.596bc38e18bbf4.75410701@mail5.mcsignup.com>
    Date: Sun, 16 Jul 2017 19:50:38 +0000
    MIME-Version: 1.0*

I am also using cloudflare on that domain.

Am I missing something? Any suggestions on how to remove the "via" and "on behalf of"?

Steve Shipway Steve Shipway · Accepted Answer · 2018-06-05T02:28:12

This is why Outlook says "On behalf of":

From: MY COMPANY <[email protected]>
Sender: MY COMPANY <[email protected]>

If there is a Sender header as well as a From header, then this indicates a 'Secretary scenario' where the massages was sent by one account (usually a mailing list, but originally a secretary) but is actually From another (such as the company CEO, who doesn't know how to use email...)

When Outlook sees a Sender header, it displays this as From $from on behalf of $sender

Mailing lists will usually set a Sender header, and in fact are supposed to according to the RFC, so that security systems such as SIDF can validate against Sender rather than against From (although DMARC doesn't do this, which is another issue).

Gmail shows “via” even if the domain is authenticated with Mailchimp and has valid SPF and DKIM records

2 Answers