After signing up, see the links page for the best web site promotion programs. It's the combination of the amount of emails that you send, and the reason why you send them, that do the trick. Consider offering a free service, answering questions about a subject that you know a lot about. You can offer your free information service throuhg a web site, advertisements, etcetera. Answer questions on discussion groups.
Most people read the postings on discussion groups, but many also read the answers.
By answering questions, or giving fair comments, you can show your e-mail signature to thousands, without annoying anyone. Put up your message on local bulletin boards, such as at school or the supermarket, where you see ads for yard sales, old cars, and furniture. Make it sound appealing. Find other free places to advertise. Free newspapers, friends websites, etc.