I just got this note (below) from our host server people.

 Can somebody recommend a fix?

 Ron
  
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 There is a serious spamming issue on your server. Your server is
 actively spamming a lot of email users by bouncing emails being sent
 to your mailing list(s) from non-member email addresses, effectively
 bouncing the pre-prepared spam to the victim. You will need to
 address and fix this issue immediately, otherwise we will have to
 block all outgoing SMTP (email) traffic originating from your
 virtual server until the problem is fixed.

  Your mailing list should be ignoring and dropping emails sent
 from non-member IPs, not bouncing them back. Most of the spam
 emails were sent by owner-(listname)@HOME-HARBOR-INN.COM

  Thanks for your immediate attention to this matter.