Rated 5 out of 5 stars

by Benno Yorck on Sept. 7, 2026 ·

A super handy plugin. I had been looking for a way to edit formatted signatures directly in Thunderbird—similar to how it's done in Outlook—for a long time.

For anyone wondering how to use it after installation:
In Thunderbird's standard view (i.e., when no settings window is open), you will find a new "Thunder Sign Editor" button in the top right corner, next to the Minimize, Maximize, and Close buttons. This button is only visible when you are in Thunderbird's email view.

A couple of suggestions for improvement:
- You cannot resize Base64-encoded images after pasting them (e.g., from Word). To do this, you have to manually adjust the HTML/CSS via Thunderbird's standard signature settings.
- It would be great if the "Thunder Sign Editor" modified the standard signature input window directly, placing the plugin's functionality where it logically belongs: right within Thunderbird's account settings input area.

Rated 1 out of 5 stars

by Cliff on June 3, 2026 ·

There is no documentation on how to start or use this add-on once installed.

Rated 3 out of 5 stars

by Orion Tech Group on Nov. 26, 2025 ·

PLEASE provide some documentation on how to use this addon. I am unable to figure out how to use it and would LOVE to be able to format a signature. I do not see any formatting capabilities in the account settings area where you edit signatures and so your screenshot does not match what I am seeing. How do I edit a signature?

Step 1: click here
Step 2: click here,
Step 3: etc

Thank you.

Rated 4 out of 5 stars

by Just Chris on Nov. 18, 2025 ·

installed it and gave it permissions, but I *cannot* find where to start it. Using TB 140.3 on Fedora42, and I can't find a button, menu item, checkbox, toolbar that opens the signature editor. What am I missing? Have reverted to TBs crappy "type in an HTML signature"

Rated 4 out of 5 stars

by Firefox user fe6673 on Aug. 8, 2025 ·

When starting and selecting, it does not load the previously saved signature. If I edit a new one, it saves it properly.

This user has a previous review of this add-on.

Rated 5 out of 5 stars

by Firefox user 3f8c3a on July 28, 2025 ·

How do I use your add-on? Any instruction would be greatly appreciated. It looks great, I just have no idea on where to start with it?

UPDATE: Thank you!

This review is for a previous version of the add-on (1.0). 

by Black Syphilis (Developer) on Aug. 2, 2025 ·

I’ve added the installation method.
Thanks for your feedback!