text_flowed is not supported

I’m not sure if this is the right place to post this issue, but text_flowed or format=flowed doesn’t seem to be respected by k9-mail. This makes the formatting of text quite awkward when reading e-mail sent by clients that support this feature (Thunderbird, mutt).

This is probably the same as issue 6327 on Google Code, but since that platform is closing, it’s good to have it here.

Basically, the headers in K9 show:

Content-Type: text/plain; charset=utf-8

while the headers of the sent message in a different e-mail client will show:

Content-Type: text/plain; charset=utf-8; format=flowed

I am using version 5.004 from F-Droid.

[qwertfisch]

It is still not supported in current version 5.007 (from F-Droid).

This seems like a violation of mail standards, namely RFC 2646 or the newer RFC 3676. The RFC describes the format=flowed feature, which allows sending mails with soft linebreaks (i.e. they are wrapped at display width) and arbitrary length of a line. This is backwards compatible so that clients not supporting it will still display them at least readable.

K-9 receiving and displaying e-mails

K-9 cannot interpret the format=flowed header flag, so those mails are always displayed with fixed linebreaks after <80 characters, no matter of my current display width. That renders wide displays useless as I will not be able reading mails over the full width.

A more severe problem arises when displaying such a mail on a device with a limited display width, e.g. smartphones. Here the text is forced into a mixture of soft (at display border) and hard (after CRLF) line breaks:

This is paragraph text that is meant to be flowed
across several lines. 
However, the sending mailer is converting it to
format=flowed text at a width 
of 79 characters, which causes it to look like
this when shown on a smartphone 
with only 50 character lines.

Sending mails with long lines is intransparent and changes content

Not only does K-9 not support displaying flowed lines, but it is also not capable of creating them.

When setting “text only” as formatting, K-9 will encode them by default as 8bit instead of quoted printable. That allows by standard only for paragraphs of 997 characters length. If you write a longer one, there will be a hard line break. You cannot see this in your compose window. It will just be inserted on sending the mail.

So this is intransparent as K-9 mail changes the content after composing the mail. This could be solved with format=flowed.

[Valodim]

this was done in #1835, just forgot to close this issue 😃