Mail indexer

[Nils Erik Svangård <nilserik gmail com>]

Hello!
I user mozilla-thunderbird as my primary mailreader (I dont like the
filtering in Evolution). I have played around with beagle (and browsed
the Evolution indexer source). If I want to index my mail do I have to
make a Thunderbird indexer or is it better to write a IMAP interface
and index my mail directly on the server.
This question applies to LICQ also, I use LICQ and Gaim parallel. LICQ
handles ICQ much better than Gaim. Do I have to write a indexer for
LICQ aswell. 
What is the diffrence between indexer and filters?
/nisse