In this subtitle the following words have the meanings indicated. “Commercial electronic mail” means electronic mail that advertises real property, goods, or services for sale or lease. “Commercial electronic mail” does not include electronic mail to which an interactive computer service provider has attached an advertisement in exchange for free use of an electronic mail account. “Interactive computer service provider” means an information service, system, or access software provider that provides or enables computer access by multiple users to a computer service. “Interactive computer service provider” includes a service or system that provides access to the Internet and systems operated or services offered by a library or educational institution.