Version 0.9.12 should now work under Thunderbird 52 and 60. However, the token [[CURSOR]] is not working anymore.
*** End update ***
Using Thunderbird, Quicktext is the perfect tool to help you quickly answer routine, repetitive emails. Quicktext performs both simple and complex tasks. The extension can insert different signatures into your emails depending on whom you are sending the email to.
Even better, you can use variables like [[TO=firstname]] to personalize your emails. You can also specify the subject and which attachments to add when creating a template for your email.
If you are a new user to Quicktext, start with reading the pages in the getting started section of the quicktext wiki. They will help you with installing and setting up Quicktext.