Rated 5 out of 5 stars

le Ho Ho ar Iúil 15, 2011 · buan-nasc

There's a workaround for TB5 compatibility.
- Download the XPI addon file
- Open it with WinRAR and extract the file "install.rdf"
- Edit install.rdf and look for "Mozilla Thunderbird".
- Change "<em:maxVersion>" value from 3.1.* to 5.*
- Save the file and update the file back into the XPI file via WinRAR
- Remove the disabled addon in TB5 and add back the updated one.
- Restart TB5

I've tried exporting and importing it. Works for me but your mileage may vary.