How to Solve the Font Not Installed Problem in Mozilla Thunderbird


Sometimes I need to use Mozilla Thunderbird as a text editor. For example, I like to use the Lobster font to display the WP Help 365 logo in my business email signature. But there is a bug in Thunderbird that reports a font not installed error when, in fact, the font I am trying to use is installed on my computer.

The issue revolves around a bug that doesn’t allow Thunderbird to correctly determine a font’s name. In other words, even though a specific font is installed on your system, Thunderbird won’t find it.

It seems that the bug was first noticed in Thunderbird version 45. Then it disappears and reappears within each new version of the software. I am now using version 45.7.0 and it’s still there.

Back to the problem at hand. In my case, the font in question is called Lobster.

The Lobster font

You can download its most current version from Pablo Impallari’s site or from Font Squirrel.

Since the font is named Lobster 1.4, Thunderbird can’t correctly read its name because of the space or the dot in the name. So, I decided to make Thunderbird recognize this font by renaming it to simply Lobster.

First, I tried to rename the font directly in the C:\Windows\Fonts folder. Obviously, that didn’t work out.

Next, I tried searching for Lobster within the registry. But all that renaming the font there did was to break it. I then wasn’t able to use that font in any software program.

Then I installed a font manager called Typograf by Neuber Software. This cool little utility has a feature that enables users to rename a font in the correct way.


After you have installed Typograf, just launch the program, select the font you want to rename and right-click on its name. In the drop-down menu select Properties. And in the Properties window click on the Rename… button.

Typograf — Properties of Lobster font

And, finally, in the Rename font name pop-up window, I renamed the font to Lobster.

Typograf — Rename font

Now, Lobster originally comes in the Open Type Font (OTF) format. For whatever reason, after renaming the Lobster font in this format, it broke.

I thought of a workaround for this problem as well.

I went to the Online Font Converter, uploaded the lobster.otf file, and converted it to True Type Font (TTF) format.

The process is super simple. First, select the output format, i.e. the format you want your font to be converted to. Then, upload the input font file by clicking on the Select Font(s) button.

Online Font Converter

A few seconds after you have uploaded the input font, you will be able to download your font in the output format as a zipped archive.

Unzip it using 7-Zip, right-click on the font, and select Install from the drop-down menu.

Once the font in its new format is installed, go to Typograf, and rename it as described above.

After all this and after you restart Thunderbird for the changes to take effect, you will be able to use the renamed font in Mozilla Thunderbird.

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