Hi, (I'm not subscribed to your ML, so please keep me in CC when replying) Disclaimer: I never used notmuch - so my questions might appear dumb. So I'm developing this personal information management (PIM) suite[0] and one aspect of PIM clearly is communication a la mail. I wonder how notmuch tracks mails. Lets assume that we have a big Maildir tree - mails move around all the time - how does notmuch (re)find them? Is there a unique way to identify an email? As far as I know isn't the message id one of them, right? [0]: https://github.com/matthiasbeyer/imag -- Mit freundlichen Grüßen, Kind regards, Matthias Beyer Proudly sent with mutt. Happily signed with gnupg.