Maildir

The Maildir e-mail format is a common way of storing email messages on a file system, rather than in a database. Each message is assigned a file with a unique name, and each mail folder is a file system directory containing these files.

A Maildir directory (often named Maildir) usually has three subdirectories named tmp, new, and cur.

• The tmp subdirectory temporarily stores e-mail messages that are in the process of being delivered. This subdirectory may also store other kinds of temporary files.
• The new subdirectory stores messages that have been delivered, but have not yet been seen by any mail application.
• The cur subdirectory stores messages that have already been seen by mail applications.

References⚑

• Wikipedia