Rated 5 out of 5 stars
SmartTemplate don't work properly after Thunderbird 12.*.* (script stop prompt and double Header) since much changes included in Thunderbird 13.
In SmartTemplate4 0.8.5.6 are this BUGS fixed, SmartTemplate4 work properly!
Please switch to SmartTemplate4, you can use your settings and Templates from SmartTemplate, no further settings after upgrade needed!