SendGrid SMTPAPI header error

I have been receiving sporadic errors from my SMTP relay provider, SendGrid, when my TN SCALE boxes send alerts - they mention a “duplicate from header detected” in the message header:

A message was received from this address by our systems that had errors in the SMTPAPI header, and cannot be processed due to the following:

  • 2 duplicate from header detected, rfc5322 states that there should be a max of 1

If you require assistance in working with the SendGrid API, please contact us at

Is there something I can do or configure to avoid such errors? Switching providers is not an option.

This is the header that SendGrid sent, for troubleshooting - there are two FROM headers indeed:

Received: by recvd-7d655c67dd-brcxr with SMTP id recvd-7d655c67dd-brcxr-1-6619049E-13
2024-04-12 09:53:34.861231969 +0000 UTC m=+2120019.675955325
Received: from morto (unknown [])
by geopod-ismtpd-2 (SG) with ESMTP id EuhMXbRsQquUJe8_9keJCA
for; Fri, 12 Apr 2024 09:53:34.633 +0000 (UTC)
Content-Type: multipart/mixed; boundary=“===============4368069502080612259==”
Subject: TrueNAS morto.saad.local: Alerts
From: =?utf-8?q?*_Saad_Morto?=
Date: Fri, 12 Apr 2024 09:43:59 -0000
Message-ID: 171291503996.871.5256644032601894608.AntH@morto.saad.local
From: =?utf-8?q?*_Saad_Morto?=
MIME-Version: 1.0

Content-Type: multipart/alternative; boundary=“===============5693217622060074595==”

Content-Type: text/plain; charset=“utf-8”
Content-Transfer-Encoding: base64


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