As part of an SOX type audit, I’ve found about 10,000 emails from about a dozen different users (some local, some remote) by doing a simple grep on the files in their respective maildir’s on the courier server. Ideally, it would be nice to just copy these emails to a new maildir and then retrieve all the mail by connecting outlook or whatever to the new maildir. The problem is that you can’t just copy messages out of one maildir into another maildir (at least I’ve never gotten that to work).