Rated 2 out of 5 stars
A nice and useful add-on which unfortunately has a very annoying bug with the latest Thunderbird (10 on) whenever the text insert is used it copies that same text to the email subject and if you forget that you send emails with odd subjects!!
Its a pity this seems not to be supported anymore (no updates since last year) as without this nasty bug it would be great.
Impossible to answer if this is a bug without knowing what your template looks like. Please use the support form on extensions.hesslow.se and tell me more about your problem