[Dovecot] Can sieve filter mail based on emails earlier in the thread?

[Hugh Davenport]

Basically I want the following scenario:

Subscribe to lots of mailing lists
- each filtered into separate folders

When I participate in a thread (by starting it, replying to it, or ... 
setting a flag on an email
in the thread)
- filter into the particular mailing list folder
- AND filter into INBOX (or another folder of my choosing)

I'm thinking for this, the first two can have rules that take into 
account In-Reference-To and
using my domain. But the third case of using a flag... that seems to 
require referencing earlier
emails in the thread.

Is this possible in sieve? Or am I barking up the wrong tree?

I believe gmail can do it, but who knows what they use for their 
filtering...

Thanks for any help anyone provides!

Cheers,

Hugh