This ought to be illegal. It amounts to stealing tons of computer resources from your victim. Doing this can bring down some unsuspecting company's email system for days at a time if they haven't put in the fixes to keep this from happening. Unfortunately, this gives the notion of doing business over the Internet a bad name. There are legitimate ways to get your message to a large number of people.
Commercial websites are relatively inexpensive.
They allow you to present your company in a positive light, show pictures of products, and even interact and transact business with your vendors and customers. By submitting your website address to various search-engines, you guarantee that when a customer is looking for keywords related to your business, they will be able to find you. There are also specialized newsgroups or communities of people with special interests that relate to your products or services. If you participate in these discussion areas, you have an excellent opportunity to present your views without the hard-sell approach that rubs so many people the wrong way. And your leads will be pre-qualified.