Enabling line wrapping in Thunderbird

I am a happy user of the daily build of Thunderbird 3. Although it is still under development, is the best email client for Linux I’ve tried so far, at least, the one that better works for me. Email search & filtering is fast and reliable.

The only thing I don’t like is that wrapping your emails to 72 characters when sending plain text is not straightforward. Once you have selected to send your emails as plain text and have set the line wrap option to 72, there is still one more option to tweak.

Thunderbird has a “feature” that sends by default all plain text with the option format=flowed, which unwraps the email in the client receiver. To turn this feature off, you have to toggle one of the options in the chrome editor:

To disable flowed paragraphs, enforcing line breaks as formatted in the message, set the preference:
mailnews.display.disable_format_flowed_support true


To disable paragraph flow when you send plain text messages, and in the plain text part of multipart messages, set the preference:
mailnews.send_plaintext_flowed false


I put it here, in case is helpful to someone else.


  1. Unfortunately, I’m not able to set line wrap in Preferences — Edit > Preferences > General only allows to set forward format, auto save, sending confirmation, attachment checking, HTML fonts and text format behavior; no line wrap (Tb 3.0.1pre hg20091129r4433)…

    Do you know the correct settings in about:config to change it manually?

    • You have to set sending plain text emails in Edit -> Account Settings -> Composition & Addressing (you should uncheck Compose in HTML format for all accounts).

      Then, look for “wrap” in your about:config


  2. Ara what would the the difference, visually and why should I care ? I am intrigued.

    • Well, the difference is that the wrapping would be always at the character 72 versus the window width.

      Wrapping at window width, nowadays, with modern resolutions, allow writing “war & peace” in a single line, which makes it a bit difficult to read.

      Imagine reading a novel where the size of the paper is 15 times the size of a normal novel…

  3. How do you set the line width at all? I can’t find that option, 72 characters or otherwise.

  4. Very useful information. Exactly what I was looking for! Looks like I finally got rid of all the line wrap problems I have been having with TB3. Now if I could only figure out out how to get newsgroup threading to work… sigh

  5. First search result on DuckDuckGo, and it solved my issue! Even years later.
    Thanks, Areta 😉