Make sure you verify all your contact information to ensure it is correct. Steps to create signature in Thunderbird with image. Hit Apply, and compose a new email to test.Once you have the text edited, copy and paste it into the signature text box and be sure to check the "Use HTML Check Box" as shown below. Click on the Insert Image button between the shortcut button and the smiley face button.Be careful not to delete any of the symbols.
THUNDERBIRD INSERT SIGNATURE SHORTCUT CODE
Open Thunderbird, go to Tools > Account Settings.If I accept Thunderbird’s suggested settings and click DONE it spends hours checking password with no end in sight. It auto-detects mostly the correct IMAP settings it suggests normal password authentication where MS says OAuth2. You are able to set your signature in Thunderbird in a variety of ways. Thunderbird won't let me add the new MS365 account.
Setting your Email Signature in Thunderbird