On Friday, 2018-12-21 at 11:54:46 GMT, David Edmondson wrote:

> On Thursday, 2018-12-20 at 07:00:08 -07, Nicolas Bock wrote:
>
>> sorry I didn't explain my problem very well. What I am looking for 
>> is to reflow (to borrow a term from NeoMutt [1]) an email message 
>> that I am _reading_ to the buffer width.  Currently format=flowed 
>> emails are simply shown as they are in the raw email body. Editing 
>> and sending emails in format=flowed works fine.
>
> Currently emacs doesn't know that the text/plain part has the
> format=flowed attribute, so it can't do anything about it.
>
> Two options occur to me:
> - ensure that emacs knows the attributes of the part so that it could be
>   extended to do something useful,

Here's a hacky patch that takes this approach. Does it do what you would
expect?

A complication is the indentation of parts, which makes it hard to set a
good value for `fill-flowed-display-column' (because you don't know the
indentation depth).

A wash function (which would be the cleaner approach, presuming that we
passed the part to all wash functions) *does* know the indentation
depth, and so could perhaps adjust the value of
`fill-flowed-encode-column' appropriately.