מנסה להבין איך עובד הFTP

[Guy]

The delivery process stores the message in the maildir by creating and writing to tmp/unique, and then moving this file to new/unique. The moving is commonly done by hard linking the file to new and then unlinking the file from tmp, but some implementations simply rename() it there. This sequence guarantees that a maildir-reading program will not see a partially-written message, as MUAs never look in tmp.

When the mail user agent process finds messages in the new directory it moves them to cur (using rename() - link then unlink strategy may result in having the message duplicated) and appends an informational suffix to the filename before reading them.

http://en.wikipedia.org/wiki/Maildir

(כמובן שאין קשר ל FTP, והכותרת לא מתאימה)