Are their hosting options just for CiviMail?

Yes, UAS CiviSMTP, provided by Shane Hill (shane at uas dot coop), Urban Alliance for Sustainability.

For a description of the service, see http://forum.civicrm.org/index.php/topic,908.0.html

There's some background information in Shane Hill's blog at http://civicrm.org/node/237

More details and information at http://www.uas.coop/civismtp-overview