from prints out the mail header lines from the invoker's mailbox.
Options:
-f file
The supplied file is examined instead of the invoker's mailbox. If the -f option is used, the user argument should not be used.
-s sender
Only mail from addresses containing the supplied string are printed.
If
user is given, the
user's mailbox, is examined instead of the invoker's own mailbox. (Privileges are required.)