Matthias,
Your advisory "Mails in HTML will not be read! Please, only plain text." needs
to be in the body of your emails, perhaps in your signature, not in your
headers. Very few recipients ever read their headers; many don't even know
headers exist.
Una
On Monday, February 9, 2026 at 09:53:53 AM MST, Matthias Apitz
<[email protected]> wrote:
Hello,
I'm adding to all my mails sent with mutt (like this one) two X-header
lines:
X-Operating-System: FreeBSD 14.0-CURRENT r1400094 (amd64)
X-message-flag: Mails in HTML will not be read! Please, only plain text.
I got informed by an reader of a mailing-list that my mails get flagged
in his OutLook mailbox with a small red flag. Technically this is added
by a Microsoft SPAM protection which adds into my mail a header among other
stuff a line like this:
```
X-Microsoft-Antispam-Mailbox-Delivery:
ucf:0;jmr:0;auth:0;dest:I;ENG:(910005)(944506478)(944626604)(4710137)(4713098)(499
9163)(920097)(930201)(20251009147)(140003);
```
I did tests with an OutLook destination I've access to and the "culprit"
seems to be only this X-header:
X-message-flag: Mails in HTML will not be read! Please, only plain text.
Any comments on what could he do or what could I do?
Thanks
matthias
--
Matthias Apitz, ✉ [email protected], http://www.unixarea.de/ +49-176-38902045
Public GnuPG key: http://www.unixarea.de/key.pub
Jens Spahn (CDU, 11.3.2025 in FAZ):
"Wir können uns verteidigen lernen oder alle Russisch lernen."
"We can learn to defend ourselves or we can all learn Russian."
"O podemos aprender a defendernos o todos podemos aprender ruso."
Ich ziehe vor, Russisch zu lernen. I prefer to learn Russian.
Yo prefiero aprender ruso.
