Send an XMPP instant message through a Jabber server to notify a user
of incoming E-Mail.

Reads the connection parameters from /etc/mailhail.conf
Reads the notification message from standard input.

Usage: mailhail JABBER-ID [SUBJECT]
                --check | -c
                --register | -r
                --help | -h
                --version | -v

This program is intended to be executed by the local mail delivery agent
after it has processed an incoming message.  A recipient and message must be
provided.  The recipient's Jabber ID may be retrieved from a database or
related to her E-Mail address by some simple heuristic.  The notification
message should contain some part of the incoming message header.

Execute with a parameter of "--check" to check the validity of the
configuration file.

For proper operation, Mail Hail must be registered with the Jabber server.
Execute once with a parameter of "--register" after installing a new
configuration file.

Examples: mailhail --check
          mailhail --register
          mailhail << EoF
          You've got mail!
          Subject: Invasion Plans
          mailhail "From the Desk of Homer" << EoF
          Subject: Pool Table