Effective sales targeting can actually be a higher form of service, so the right products find the right people. Both your business and your customers will benefit. Realize that your site could be visited by someone who does not yet realize they need your product or service. Foster new relationships with 'About Company XYZ'-style web pages. Absolutely void mass mailings using email or regular mail.
Customers expect confidentiality from ALL merchants with whom they share their personal information.
Honor that expectation. This type of marketing is fine for one time sales, but in an effort to secure customer retention, this approach can be deadly. Most importantly, remember that winning at E-Commerce involves more than just one sale per customer. With the added revenue gained through the higher margin of R-Commerce, offer your customers the opportunity for collaboration with you and your company via newsletters or chat rooms. Or better yet, offer something free - a free daily quote, free company news, or perhaps even a free product.