[Dovecot] Global FTS index?

[Jason Fesler]

> Is my assumption correct, that there is no way to do a search over a big IMAP
> folder hierarchy in a reasonable amount of time, because each folder has to
> be 'selected', and only one folder can be selected at once?

This isn't 100% what you're looking for, but.. consider looking at 
"mairix".   It does do full text search of mbox and maildir;  it is a cli.
Give it a search, and it populates a mail folder (using hardlinks if 
possible) with the results.

I use it when I want to search my archives; the speed makes up for it not 
being native to the imap client.

http://www.rc0.org.uk/mairix/