Beagle and Thunderbird

Hi,

Recently I've upgrade from 0.2.18 to 0.3.8. After solving a problem
with the mime type detection I'm still having trouble to get my
Thunderbird data indexed.

### First try:
> beagled --fg --debug --backend Thunderbird
...
Debug: Starting backend: 'Thunderbird'
Debug: Starting Thunderbird backend
Debug: No Thunderbird data to index in /home/steve/.beagle/Indexes/ThunderbirdIndex/ToIndex
...

What's expected in the "ToIndex" subdirectory (it even doesn't exist)?

### Second try:
I've created the "ToIndex" directory manually, re-started beagled.
...
Debug: Starting backend: 'Thunderbird'
Debug: Starting Thunderbird backend
Debug: New Thunderbird indexable generator launched for /home/steve/.beagle/Indexes/ThunderbirdIndex/ToIndex
Debug: Thunderbird backend done in 0.006222s
...

But nothing more happens.

Thunderbird is enabled in beagle-settings' "Data Source" tab. Any idea
what I'm missing ?

Thanks & rgds,
  Stephan.