Hm, so in Vivaldi it just shows
But in Thunderbird it says:
Clicking on "2 more" shows the other supposed from addresses are:
multipart/alternative <>
And:
the-message-id-hash@dndsanctuary.eu
It's likely Gmail parses it the same way, but then decides to reject the message.
Edit: the one from Wordpress looks like this:
…@gmail.com; Mon, 21 Mar 2022 20:11:30 +0100
To: …@gmail.com
Subject: Site nonsense
Date: Mon, 21 Mar 2022 19:11:30 +0000
From: WordPress <…@…>
Message-ID: <3gsjHp42Em8qSFqoTD8HHjC7ltZYffugefPCV0f8tE@fransdejonge.com>
X-Mailer: PHPMailer 6.5.3 (https://github.com/PHPMailer/PHPMailer)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
I don't know the email header spec but that indentation in the email from Elkarte looks suspicious?
Edit 2:
In any case, running it through a header parser shows this is indeed the entire from field:
"The DnD Sanctuary" <thefromemail@dndsanctuary.eu> Return-Path: thefromemail@dndsanctuary.eu Date: Wed, 23 Mar 2022 07:22:54 -0000 X-Mailer: ELK Mime-Version: 1.0 Content-Type: multipart/alternative; boundary="ELK-83f0fe058f0cf03cf18bffd39d24f144" Content-Transfer-Encoding: 7bit Message-ID: <b9d5348f83cc8893f56575710c4291cb-@dndsanctuary.eu>
Removing the single-space indentation seems to result in correct parsing.