bsd-mailx(1) - send and receive mail
-a      Specify additional header fields on the command line such as "X-Loop: foo@bar" etc.  You have to
        use quotes if the string contains spaces.  This argument may be specified more than once, the
        headers will then be concatenated.
-b bcc-addr
        Send blind carbon copies to bcc-addr.
-c cc-addr
        Send carbon copies to list of users.  cc-addr should be a comma separated list of names.
-d      Causes mail to output all sorts of information useful for debugging mail.
-E      Don't send messages with an empty body.
-f [file]
        Read in the contents of your mailbox (or the specified file) for processing; when you quit, mail
        writes undeleted messages back to this file.
-I      Forces mail to run in interactive mode, even when input is not a terminal.  In particular, the
        special ~ command character, used when sending mail, is only available interactively.
-i      Ignore tty interrupt signals.  This is particularly useful when using mail on noisy phone lines.
-N      Inhibits initial display of message headers when reading mail or editing a mail folder.
-n      Inhibits reading /etc/mail.rc upon startup.
-s subject
        Specify subject on command line (only the first argument after the -s flag is used as a subject; be
        careful to quote subjects containing spaces).
-u user
        Equivalent to:

              $ mail -f /var/mail/user

        except that locking is done.
-v      Verbose mode.  The details of delivery are displayed on the user's terminal.