The mailboxes in the message store are stored in a hash structure for fast searching. Consequently, to find the directory that contains a particular user’s mailbox, use the hashdir utility.
This utility identifies the directory that contains the message store for a particular account. This utility reports the relative path to the message store, such as d1/a7/. The path is relative to the directory level just before the one based on the user ID. The utility sends the path information to the standard output.
For example, to find the relative path to the mailbox for user crowe: