For inbound customers including Email Gateway, Email Forwarding and Spam Filtering the headers we inject are:



Header Key
Header Description and Example Value
X-HalonDuo-ID
Unique Message ID

20fsdf1859-210c-11ea-9b56-5b3414d4d306
X-HalonDuo-CID
Customer ID of the account owning the inbound domain

<numerical, natural number>
X-HalonDuo-SID
Service ID of inbound domain

<numerical, natural number>
X-HalonDuo-Scores
JSON-encoded list of spam scores assigned to the message

{"rpd":"unknown", "sa":0, "sa_scores":{"FREEMAIL_FROM":0.001, "HTML_MESSAGE":0.001}}
Envelope-Sender
Identifies the SMTP "MAIL FROM" provided by the sending server

bob@gmail.com
Received
We prepend a Received header with information identifying the server which processed the message, as required by RFC-5321.

Received: from mail-yb1-f173.google.com (mail-yb1-f173.google.com [209.85.219.173]) by inbound4.eu.mailhop.org (Halon) with ESMTPS; Tue, 17 Dec 2019
Received-SPF
Result of our SPF check.

none | hardfail | softfail | pass
Authentication-Results

Extended SPF / DKIM / DMARC check results

<our server hostname>; spf=softfail smtp.mailfrom=example.com; dkim=pass header.d=example.com header.s=selector header.a=rsa-sha256 header.b=<hash>; dmarc=none header.from=example.com;
ARC-Seal
ARC-Message-Signature
ARC-Authentication-Results
Authenticated Received Chain (ARC) headers, as described in RFC-8617.



Outbound email have the headers:


X-Mail-Handler: DuoCircle Outbound SMTP

X-Originating-IP: xxx.xxx.xxx.xxx

X-Report-Abuse-To: abuse@duocircle.com (see https://support.duocircle.com/support/solutions/articles/5000540958-duocircle-standard-smtp-abuse-information for abuse reporting information)

X-MHO-User: xxxxxxx