Switch Between HTML And Plain Text Emails In Thunderbird

Martin Brinkmann
Aug 16, 2010
Updated • Mar 17, 2018
Email, Thunderbird

Emails can be composed as HTML or plain text messages. HTML emails mainly offer the advantage of better formatting options over plain text emails from a user's point of view. Internet marketers and companies may use them for tracking purposes.

HTML emails support text formatting options such as changing the font size, using bold or underline, displaying lists or images. While that is great to make emails look prettier, the downside is that HTML emails pose security and privacy risks.

It is for instance possible to embed an - often invisible 1x1 pixel image - in the HTML email to track if the recipient has read the email (opened it). There have also been cases where maliciously modified objects were included in emails.

The Thunderbird email client supports both plain text and HTML emails. The account settings hold the default preference for each email account in the mail client. This only affects email messages that are created in Thunderbird, not messages that are received.

html emails
html emails

You open the Account Settings with a click on Tools > Account Settings. If the menu bar is not displayed by default, unhide it with a tap on the Alt-key on the keyboard.

Go to Composition & Addressing, and check or uncheck the "Compose messages in HTML format" option there.

The preference for incoming emails is found under View > Message Body As. Here it is possible to switch from the default Original HTML to Simple HTML or Plain Text.

incoming emails plain text
incoming emails plain text

This preference is valid for all incoming emails, regardless of the email address they have been sent to.

Original HTML

Original HTML displays emails as HTML messages. This may include that images do get downloaded from remote servers (something that trackers often do) and that JavaScript may be executed.

Thunderbird users may disable remote content in messages in the Options under Privacy > Allow remote content in messages.

If you choose View – Message Body As – Original HTML, then you see HTML messages in their original form.

Simple HTML

Simple HTML takes the best of both worlds. It preserves the formatting of HTML emails but blocks JavaScript code and remotely downloaded images.

If you choose View – Message Body As – Simple HTML, then you see HTML messages in a simplified form. Thunderbird does not run JavaScript code, and does not download remote images. Simple HTML preserves basic HTML formatting.

Plain text

If you select plain text as the view option in Thunderbird, all emails are displayed as plain text. This is true even for messages that were sent as HTML emails.

If a message is multi-part, only the plain text part is displayed. Note that Thunderbird may enhance plain text messages with certain text formatting features such aa:


  • Bold, italic and underlined text.
  • Smileys displayed as images.
  • Attached images displayed in the body of the message.
  • Links displayed in blue, and underlined.
  • Flowed paragraphs (if the message was sent using flowed paragraphs)
  • Quoted paragraphs outlined with colored bars (if the message was sent using flowed paragraphs)
  • Signatures displayed in gray.

The supported smileys are:
:-) :) smile
:-D laughing
:-( :( frown
:-[ embarassed
;-) ;) wink
:-\ undecided
:-P ;-P tongue
=-O surprise

:-* kiss
>:o >:-o yell
8-) cool
:-$ money
:-! foot
O:-) innocent
:'( cry
:-X sealed

It sometimes may be necessary to write HTML emails and plain text emails, depending on the recipient. While it is possible to switch the format in the account settings, it is possible to make a temporary switch when composing emails.

Holding down the Shift key before clicking on create a new message, or one of the reply options, switches from the default writing mode to the other.

Thunderbird will automatically display the plain text email editor if HTML emails are the default, and vice verse if the Shift key is pressed.

The composition window will display HTML elements like bold or underline if an HTML message is composed, or no text formatting options if it is a plain text email.

HTML Email composition window

html email
html email

Plain Text composition window

plain text email
plain text email

Holding down the shift key is the fastest way of switching between HTML and plain text composition windows.

Please note that the Shift-key modifier works only if you click on the write or reply buttons in the Thunderbird interface. It does not work if you use keyboard shortcuts such as Ctrl-N.

Switch Between HTML And Plain Text Emails In Thunderbird
Article Name
Switch Between HTML And Plain Text Emails In Thunderbird
The tutorial offers detailed instructions on configuring HTML and plain text email send and receive options of the email client Thunderbird, and how to switch between them when composing emails.
Ghacks Technology News

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  1. JMGG said on January 19, 2012 at 8:25 am

    You said that Outlook isn’t your main email client, so which is your main one?

    1. BalaC said on January 19, 2012 at 9:42 am

      I think its thunderbird

    2. Martin Brinkmann said on January 19, 2012 at 10:15 am

      It is Mozilla Thunderbird.

  2. Salaam said on September 24, 2012 at 9:52 pm

    Awesome! This actually solved my problem… what a stupid bug.

  3. Claud said on December 19, 2012 at 2:08 am

    If this is the same bug that I’ve encountered, there may be another fix: (1) hover over open Outlook item in Taskbar, cursor up to hover over Outlook window item, and right-click; (2) this should give you Restore / Move / Size / Minimize / Maximize — choose Move or Size; (3) use your cursor keys, going arbitrarily N/S/E/W, to try to move or size the Outlook window back into view. Basically, the app behaves as though it were open in a 0x0 window, or at a location that’s offscreen, and this will frequently work to resize and/or move the window. Don’t forget to close while resized/moved, so that Outlook remembers the size/position for next time.

    1. Lynda said on February 12, 2013 at 3:37 pm

      THANK YOU Claude!!! I could get the main window to launch but could not get any other message window to show on the desktop. You are my hero!!!!

    2. Chad said on November 20, 2018 at 4:24 pm

      Solved my issue! 6 years later and this is still problem…

    3. Ivan X said on January 21, 2021 at 4:50 pm

      Fantastic. Thank you. Size did the trick.

  4. Andrew said on October 26, 2013 at 7:06 am

    This solved my Outlook problem, too. Thank you. :)

  5. Charles said on December 7, 2013 at 7:23 pm

    Thank you so much, this started happening to me today and was causing big problems. You are a life saver, I hope I can help you in some way some day.

  6. garth said on November 7, 2014 at 7:13 pm

    You are a god – thank you!

  7. Faisal said on February 9, 2015 at 10:09 am

    thanks a lot…. work like charm.. :-)

  8. Simon said on March 24, 2015 at 11:36 pm

    Yah…thanks Claude. I’ve been having the same problem and tried all the suggestions…your solution was the answer. It had resized itself to a 0/0 box. Cheers

  9. Olu said on April 14, 2015 at 1:35 pm

    Excellent post. This had me baffled even trying to accurately describe the problem. This fixed it for me.
    Thank you

  10. Coenig said on July 23, 2015 at 7:36 am

    Thanks a lot for the article. Don’t know why it happenend, don’t know how it got fixed, but it was really annoying and now it works :-)

  11. Fali said on January 20, 2016 at 4:19 pm

    Thanks a lot. I was facing this issue from past 3 week. I tried everything but no resolution. The issue was happening intermittently and mainly when I was changing the display of screen ( as i use 2 monitors). The only option i had was to do system restore. But thanks to you.

    1. MIki said on January 10, 2019 at 11:54 am

      I’ve been tried to sole this problem for 12hours. Your comment about changing the display of screen helped me a lot!! Thanks!!

  12. Christina said on January 20, 2016 at 6:14 pm

    Thank you…don’t know why this happened but your instructions helped me fix it. Running Windows 10 and office pro 2007

  13. Oz said on July 22, 2016 at 3:20 pm

    Great tip! Thanks!

  14. Tracy said on September 1, 2016 at 4:48 pm

    Worked for me, too – thank you!!!

  15. shawn said on September 9, 2016 at 10:25 am

    It’s Worked for me, too
    thank you very much!

  16. Jari said on October 31, 2016 at 11:53 am

    I had a similar issue with Outlook 2013 on Windows 10 and this helped me to fix it. Thank you very much!

  17. Michel H said on November 30, 2016 at 11:08 pm

    Thank you so much. Solved!
    Considering you published this in 2012, incredible not been debugged by Microsoft.
    Thank you again. M

  18. Ziad Bitar said on January 9, 2017 at 2:00 am

    This problem was faced by only one user logging to TS 2008 r2 using outlook 2010.The issue was resolved.


  19. Anonymous said on February 15, 2017 at 5:24 pm

    Great tip. Thank you!!!! If it helps, I had to use the Control Key and the arrow keys at the same time to bring my window back into view. Worked like a charm.

  20. Rochelle said on March 6, 2017 at 11:59 am

    Thank you, this worked !!!!

  21. anom1234 said on May 20, 2018 at 11:20 pm

    Man, you are a fucking god. Thanks a lot, what an annoying bug!!

  22. JC said on October 12, 2020 at 2:14 pm

    Awesome, this post solved the issue. Many thanks!

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