Inexpensive Bulk Mail SW Advice - Part II

After reading answers from my first one and a couple after I closed, I realized that I didn't give enough info.  Yes, I am brand new to bulk email (and only a year in I.T.).  I am in a mid-sized family-owned real estate co. that currently sends out a biweekly email to 1,000 recipients (saved in Excel).  We have a Microsoft SBS 2003 server and run Exchange.  One person suggested hosting offsite so we don't get blacklisted, but my boss does like the security of keeping everything inside.  Since we are small, we are looking for an inexpensive solution, but he also wants it to be almost all self-managed, such as people clicking on unsubscribe or replying and putting Unsubscribe in the Subject Line or at the worst we can manage it with a click of a button.  Lastly, we want to send html embedded in the body of the email, not attached like an icon.
 
So far, the following recommendations have come in:  listserv, Cake Mail, Constant Contact, iContact, and SmartSerialMail, the latter of which I have downloaded and successfully sent an embedded html.