[Dovecot] Search results as virtual folders

[Daniel L. Miller]

This may have been asked before - if so I apologize.

Some mail clients - like Thunderbird - can provide a virtual folder or 
"saved search" to provide a list of mails that match certain criteria.  
Obviously, unless special client-side caching is implemented - which 
Thunderbird (my own client of choice) - does not, generation of these 
folders take time.  Does Dovecot have any provision for generating such 
virtual folders?  Possibly as the result of a sieve script?
-- 
Daniel