Already built and running fine thanks mike-even tell you what it is if you wish to PM me.
Tech advice here is pretty good - some might use it for work , some personal some both.
With the marketing - I think it just depends how you use it - only send to those who ask for information, and you have to make the unsubscribe easy to use. In fact outfits like Vertical Response will start asking you questions if your unsubscribe or bounce rates trip a certain number.