How to Add Your Email Signature to Thunderbird

To add your htmlsig signature to Thunderbird, download your signature as an HTML file, then in Account Settings check Attach the signature from a file instead and choose that file.

Step 1: Download your signature file

1. Open your signature in htmlsig. You can find all of your signatures on the Signatures page.
2. Click Download. A file called signature.html is saved to your computer.
3. Move the file somewhere permanent, such as your Documents folder. Thunderbird reads the file each time you write an email, so don't delete it.

Step 2: Attach it in Thunderbird

1. Open Thunderbird, click the menu button (three lines) and choose Account Settings. You can also use Tools > Account Settings.
2. Select your email address in the left panel.
3. Check Attach the signature from a file instead (text, HTML, or image), click Choose… and select the signature.html file you downloaded.
4. Close the Account Settings tab. Your changes are saved automatically.

Write a new email to check that your signature appears.

If you'd rather not keep a file around, you can paste the code instead: click Source Code on your signature page, click Copy to Clipboard, then in Thunderbird's Account Settings check Use HTML and paste the code into the Signature text box. If you edit your signature in htmlsig later, repeat these steps so Thunderbird gets the new version.