Dearborn, Mich.---In the latest example of a major manufacturer moving to support its retail channel on the Web, General Motors Corp. this week signed a three-year deal with Valassis Communications Inc. to provide targeted print direct mail and Internet e-mail marketing services to dealers. The deal calls for GM to underwrite and support mailers that call for customers to bring their vehicles in for service. A bar code will enable the dealer to set up a customer prospect database and track and cultivate the customer relationship. Meanwhile, GM will use the same information to build a master database. The move follows the formation of Carabunga.com, a service aimed at auto dealers interested in cultivating customer relationships on the Internet. The value of the Valassis agreement was not disclosed.