Send Format=Flowed Messages

Concept

format=flowed-style messages (or f=f for short) are text/plain messages that consist of paragraphs which a receiver’s mail client may reformat to its own needs, which mostly means to customize line lengths regardless of what the sender sent. Technically this is achieved by letting lines of a “flowable” paragraph end in spaces except for the last line.

While for text-mode clients like NeoMutt it’s best to assume only a standard 80×24 character cell terminal, it may be desired to let the receiver decide completely how to view a message.

NeoMutt Support

NeoMutt only supports setting the required format=flowed MIME parameter on outgoing messages if the $text_flowed variable is set, specifically it does not add the trailing spaces.

After editing, NeoMutt properly space-stuffs the message. Space-stuffing is required by RFC3676, defining format=flowed, and means to prepend a space to:

• all lines starting with a space

• lines starting with the word From followed by space

• all lines starting with >, which is not intended to be a quote character

Note

NeoMutt only supports space-stuffing for the first two types of lines but not for the third: It is impossible to safely detect whether a leading > character starts a quote or not.

All leading spaces are to be removed by receiving clients to restore the original message prior to further processing.

Editor Considerations

As NeoMutt provides no additional features to compose f=f messages, it’s completely up to the user and his editor to produce proper messages. Please consider your editor’s documentation if you intend to send f=f messages.

For example, vim provides the w flag for its formatoptions setting to assist in creating f=f messages, see :help fo-table for details.

Reformatting

NeoMutt has some support for reformatting when viewing and replying to format=flowed messages. In order to take advantage of these, $reflow_text must be set.

• Paragraphs are automatically reflowed and wrapped at a width specified by $reflow_wrap.

• In its original format, the quoting style of format=flowed messages can be difficult to read, and doesn’t intermix well with non-flowed replies. Setting $reflow_space_quotes adds spaces after each level of quoting when in the pager and replying in a non-flowed format (i.e. with $text_flowed unset).

• If $reflow_space_quotes is unset, NeoMutt will still add one trailing space after all the quotes in the pager (but not when replying).

📷 Screenshot Needed

Subject: Flowed vs fixed text in the pager

Description: The NeoMutt pager showing a format=flowed message with $reflow_text enabled, demonstrating how paragraphs are reflowed and wrapped cleanly to the terminal width. Ideally show a quoted reply with $reflow_space_quotes set, displaying the added spaces between quote level markers.

Highlights: How reflowed paragraphs wrap cleanly compared to fixed-width text with hard line breaks, and how $reflow_space_quotes improves readability by adding spaces after > quote markers.