I have an IMAP account with over 10 years' worth of emails in it, and I'd like to be able to search it quickly from my Windows machine. I'm looking for something that will give me an **indexed** search of my email (ideally without changing anything on the IMAP server, but that's not vital).

I don't mind if it keeps a mirror on my Windows PC and indexes and searches that locally, as long it keeps itself up to date automatically. I use Thunderbird as a client, but I don't mind using a separate application to search.