How to change the font of mails in Thunderbird - gHacks Tech News

How to change the font of mails in Thunderbird

Thunderbird is my desktop email client of choice and one of the reasons for that is that it is highly customizable. Not only by installing extensions that change the client's behavior, but also by making changes to settings that the program ships with.  I was recently asked if there is a way to increase the font size of the Ghacks newsletter in Thunderbird, and sure thing, there are  several options to do so locally.

There are two ways to change the font size of emails in Thunderbird, one is only making the changes temporarily for the session while the other one is permanently making the change.

The easiest way to change the font size is to hold down the Ctrl key on the keyboard and use the mouse wheel to increase or decrease it. The changes are visible right away in the mail pane so that you can use this method to adjust the font size to a level you are comfortable with. You can alternatively use Ctrl and the minus or plus keys on the keyboard, or click on View > Zoom to use the menu to change the font size. The shortcut Ctrl and 0 resets the zoom level to the default value.

thunderbird text zoom

The changes that you make here are valid for the session which means that they are automatically reset on the next start of the email client.

If you have general issues reading emails because of the size they are displayed in, you may prefer a solution that changes the font size of emails permanently.

To do so click on Tools > Options in the menu. This opens the settings menu of the email program. Here you need to click on Display > Formatting to display all font related formatting options Thunderbird makes available.

thunderbird font formatting

Use the pulldown menus to change the default font size or font type, or click on the advanced button for detailed font formatting options.

thunderbird fonts

Here you can modify the default font for proportional, serif, sans-serif and monospace contents, set a minimum font size and select a region you want your fonts be optimized for. The changes that you make in the menus here are permanent until you modify them again here.

You can still change the font size for individual sessions using the first method described in this post though.


We need your help

Advertising revenue is falling fast across the Internet, and independently-run sites like Ghacks are hit hardest by it. The advertising model in its current form is coming to an end, and we have to find other ways to continue operating this site.

We are committed to keeping our content free and independent, which means no paywalls, no sponsored posts, no annoying ad formats or subscription fees.

If you like our content, and would like to help, please consider making a contribution:

Previous Post: «
Next Post: »


  1. Patrick said on January 18, 2013 at 5:30 pm

    Martin: Thanks a million for this tip. As a sufferer of AMD (Age-related Macular Degeneration) this tip has improved my computer usage 10 fold.


  2. Hector said on January 18, 2013 at 8:34 pm

    Note that these settings affect the fonts displayed in the mail you receive and while composing messages, but not the fonts embedded in outgoing mail. For the latter, keep the default settings in the Composition tab.

    To adjust the fonts for menus and message lists, there is an add-on:

  3. lookmann said on January 20, 2013 at 4:57 pm

    Hi Martin,
    may be off-topic, but i need your tip badly.
    How to make the links in received mails live?
    i have to copy/paste them in the address bar every time i receive a link .
    this happens in TBird only.

    1. Martin Brinkmann said on January 20, 2013 at 6:05 pm
  4. Bill, Edmonton, Alberta, Canada said on January 22, 2013 at 3:33 am

    In my Thunderbird 17.0.2, using Ctrl+mouse wheel simply activates its scroll functionality. There’s no visible effect on the font size.

    Ctrl++ and Ctrl+- work as described above and as indicated by the TB menu View/Zoom submenu.

    Am I missing something? Thanks for the article!

  5. Junior Jackson said on January 22, 2013 at 6:24 am

    Maybe I’m missing something but what’s wrong with just clicking the small “A” and the large “A” representing smaller and larger font size respectively (right next to the “choose color font” option on the formatting bar), when highlighting the text?

    1. Martin Brinkmann said on January 22, 2013 at 11:23 am

      Those buttons are only displayed when you write emails and not when you read them, at least on my system.

  6. Junior Jackson said on January 23, 2013 at 6:18 am

    Ok, Martin. I didn’t realize you were just referring to the reading mail and not writing mail, too.

  7. Jim McCauley Oxford Ms said on August 19, 2013 at 2:42 pm

    When I type e-mails the setting for the font size is too small………I have clicked on the “A” to make it larger, however after a sentence or two it just reverts back to the small size. How can I set the font size setting to keep it at a larger size?

  8. Anonymous said on April 15, 2017 at 7:03 pm

    It is not working at all in Thunderbird 45.8.0

  9. Alfredo Saab said on February 11, 2018 at 8:41 pm

    The solutions proposed do not work (Any of them).

Leave a Reply

Check the box to consent to your data being stored in line with the guidelines set out in our privacy policy

Please note that your comment may not appear immediately after you post it.