On Apr 13, 2014, at 10:25 PM, Keith Keller <kkeller at wombat.san-francisco.ca.us> wrote: > > In the context of the OP, when mutt tries to deal with a message (e.g., > deleting, moving to a folder), it can be boatloads faster, since > handling the message works on a small file which contains just that > message. Deleting a message from an mbox mailbox, for example, requires > rewriting the entire changed mbox file to disk (minus the deleted message). > Deleting a message from a Maildir mailbox is just removing one file from > a directory. HOWEVER. When a directory grows too large, the OS can take a long time to seek through the directory, which can cause its own set of problems. And this makes cleaning out a maildir directory selectively a real pain. Maildir really could do with a hashing mechanism. --Russell