Support for format=flowed

[DamienCassou]

Hi,

I, too, thought about doing exactly the same 2 or 3 years ago but my understanding of text properties was even poorer than it is now. Thank you for doing it. Another reason for me to not invest time on it is it's apparent poor support in mail user agents:

• Emacs message-mode doesn't support it
• K9-Mail has an implementation, but it hasn't been released yet
• Zimbra doesn't support it either
• Thunderbird apparently supports it but says: "It is a interesting standard that just didn't catch on"

What is your opinion on it?

[legoscia]

The user agent I primarily had in mind is the Gmail app on Android. I just couldn't stand seeing the messages I sent from Emacs when reviewing a mailing list thread on my phone. Emacs message-mode does support displaying flowed messages, though for some reason the default value of `fill-flowed-display-column` is just `fill-column`. I customized it and set it to `(min fill-column (- (window-width) 5))`, such that the display width adapts to the width of my Emacs window. I guess many mail clients are not very interested in implementing this, since they assume that a client that can send format=flowed messages will also send an HTML alternative. I've been thinking about making Emacs do that, composing messages in Markdown or Org, and having them converted to HTML automatically before sending — I seem to remember seeing an implementation of just that somewhere. Of course, the question then is what do you send as the text/plain alternative? I've configured Emacs to prefer text/plain over text/html, and I dislike seeing raw Markdown in the text/plain part, as some web sites apparently do. I guess improving Emacs to make sending HTML messages in an Emacsy way is ultimately the way forward. Meanwhile, messages-are-flowing hopefully makes my messages more readable to at least some people.

[aspiers]

I was pretty confused by this discussion :-) But I think I managed to figure it out, so posting here in case it helps someone else.

Presumably the whole point of this package is to support format=flowed, but looking at the code I see no evidence of it changing the raw content of the buffer - it only changes the text properties so that an extra newline symbol is displayed. But for f=f to work, certain things must happen like spaces being appended to the end of lines where reflowing is desired. So how is this package supposed to enable f=f behaviour? AFAICS the answer lies in the fact that the package turns on the use-hard-newlines minor mode, and that gnus/flow-fill.el defines fill-flowed-encode to append spaces to the end of lines when use-hard-newlines is enabled. There's another function fill-flowed in the same file which gets called by mm-inline-text in gnus/mm-view.el. Unfortunately these functions are all totally undocumented so it's not immediately clear what they're doing. I did find this though:

https://www.gnu.org/software/emacs/manual/html_node/emacs-mime/Flowed-text.html

The main problem for me is that while I'm writing (plain text) mail in emacs, I am not sending it via gnus or indeed via emacs at all - I'm sending it via mutt. So none of this flowed text support which ships with emacs is particularly helpful for me right now, and neither is messages-are-flowing :-/ Any suggestions for how to improve things for my use case are very gratefully received!

[aspiers]

I've created https://www.emacswiki.org/emacs/FormatFlowed to try to make sense of all of this.

[legoscia]

You got it right: right now this is rather entwined with message-mode. I commented about a potential way to get emacs+mutt to do the right thing in #4, but I haven't tried it myself.

[aspiers]

Ah that's useful info, thanks!