format=flowed involves putting a single space at the end of line text which is not the end of a paragraph. When 'decoding' a message so-labelled it would be plausible for Mutt to remove such trailing spaces. It would also be plausible for it to leave them in.
When is hateful is for it to _double_ such spaces, so that continued lines now end in two space characters -- and meaning that if I'm quoting somebody else's message, I'm quoting characters that neither she nor her mailer inserted. Moreover, if I attempt to reflow such a paragraph (in the old-fasioned way, ignoring f=f) by using Vim's gq command words with spurious, and curous, double spaces between them can end up in the middle of lines. Vim can cope with ">"s denoting quoted paragraphs, leaving the quote characters at the start of each line while flowing words around them. And it handles fine either zero or one space characters at the end of a line. But if a line ends in multiple space characters then it presumes, not unreasonably, that they are there for a purpose, so preserves them in the reflowed text -- yielding the gaps between words. I'd spotted that messages which go gappy on quoting were all sent by Thunderbird, so I was about to hate Thunderbird for inserting the spurious spaces. But it appears Thunderbird is following the rules (it just that only all the f=f mail I receive is from Thunderbird users) -- the hate for the gaps in quoting is definitely with Mutt. (You can see it by viewing a f=f message then piping it to an external viewer with pipe_decode=no and then pipe_decode=yes.) Smylers
