Philippe Vaucher <philippe.vaucher@gmail.com> writes:

>> [Again, please consider using plain-text, not HTML, in your messages.]
>
> I try to do that each time, e.g this message should be plain text. Tell me if it isn't. I reply from gmail and select "remove formatting".

If I am not mistaken, to send plaintext with Gmail, one must open the
"⋮" menu (three vertical dots) and pick "Plain text mode".  "Remove
formatting" merely strips away bold/italic/…, but the outgoing mail is
still HTML.