Re: Unexpected fill-paragraph behaviour in message-mode

[Ryan Kavanagh <rak@rak.ac>]

On Mon, Feb 13, 2023 at 03:35:08PM +0200, Eli Zaretskii wrote:
> This problem doesn't happen if the buffer has the expected separator
> line saying "--text follows this line--".  Why are you trying to use
> message-mode in a buffer that is not formatted as an email message?

The line was missing because I use (neo)mutt as my email client and I
decided to try setting my editor to "emacsclient -c", but mutt does not
insert said separator. Is there an alternate mode I should be using when
compose emails with non-emacs MUAs?

> Without that separator, message-mode doesn't know where the headers
> end and the message body begins.

Quickly skimming message.el, it looks like message-mode (only?) supports
mail and news. In those cases, RFC 5322 §2.1 [0] and RFC 5536 §2 [1]
give the following separator:

    The body is simply a sequence of characters that follows the header
    section and is separated from the header section by an empty line
    (i.e., a line with nothing preceding the CRLF).

Looking at the source in message.el, it usually finds the separation
between header and body using:

    (re-search-forward
           (concat "^" (regexp-quote mail-header-separator) "$")

It would be nice to be able to use emacs as an editor with non-emacs
MUAs, so I wonder if I shouldn't file a bug report asking message.el to
fallback on the RFC (and set mail-header-separator to "") in the cases
where "--text follows this line--" is missing.

Best wishes,
Ryan

[0] https://www.rfc-editor.org/rfc/rfc5322#section-2.1
[1] https://www.rfc-editor.org/rfc/rfc5536#section-2

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