On Mon, Feb 16, 2026 at 08:28:44AM +0100, Nicola Pinna <[email protected]> wrote:
> <On Sat, Feb 14, 2026 at 06:15:26PM +0000, Nuno Silva via Mutt-users wrote:> > > > On 2026-02-09, Matthias Apitz 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 Hi, I expect that it's unlikely that recipients of your emails would see the X-message-flag header. I might be wrong, but many non-mutt mail clients I see don't show many headers at all (not even the From: header!). You have to out of your way to see them. It probably makes more sense to remove that header, and add your plea to your signature. That way, recipients can actually see it without additional/unlikely effort on their part. However, if you want to accept that other people will continue to do what they do, and you have no control over that, I have a program that might help you (raf.org/textmail). It converts HTML emails to plain text, and Excel attachments to CSV, and Word/PDF attachments to text, delete images, etc. If your email is delivered in a way that you can use procmail to filter it before it's saved, you could convert incoming emails to plain text before you see it. cheers, raf
