Updated logic for message-display.

  This simplifies things as part of #194.

  TODO:  Split headers on newline/comma and allow them to be
 bundled.

  e.g. This:
     To: foo@bar.com, example@example.com, steve@steve.com

  should become:

    To: foo@bar.com,
     example@example.com,
     steve@steve.com