MaildirフォーマットD. J. Bernstein Internet mail Using maildir format Why should I use maildir? Two words: no locks. An MUA can read and delete messages while new mail is being delivered: each message is stored in a separate file with a unique name, so it isn't affected by operations on other messages. An MUA doesn't have to worry about partially delivered mail: each message is safely written to disk in the tmp subd
