The readership utility reports on how many users other than the mailbox owner have read messages in a shared IMAP folder.
An owner of a IMAP folder may grant permission for others to read mail in the folder. A folder that others are allowed to access is called a shared folder. Administrators can use the readership utility to see how many users other than the owner are accessing a shared folder.
This utility scans all mailboxes and produces one line of output per shared folder, reporting the number of readers followed by a space and the name of the mailbox.
Each reader is a distinct authentication identity that has selected the shared folder within the past specified number of days. Users are not counted as reading their own personal mailboxes. Personal mailboxes are not reported unless there is at least one reader other than the folder’s owner.
For example, the following command counts as a reader any identity that has selected the shared IMAP folder within the last 15 days:
readership -d 15