/var/mail : User mailbox files (optional)

Purpose

The mail spool must be accessible through /var/mail and the mail spool files must take the form <username>. [41]

User mailbox files in this location must be stored in the standard UNIX mailbox format.

The logical location for this directory was changed from /var/spool/mail in order to bring FHS in-line with nearly every UNIX implementation. This change is important for inter-operability since a single /var/mail is often shared between multiple hosts and multiple UNIX implementations (despite NFS locking issues).

It is important to note that there is no requirement to physically move the mail spool to this location. However, programs and header files must be changed to use /var/mail.