Abstract: The invention enables a short (typically 30s) advertising or other film to be multicast over the Internet. The film is embedded in the body of an electronic mail message for the network (rather than being sent as an attachment) so that the film runs as soon as the message is viewed; and the message may include means to send a reply automatically whenever the message is opened or forwarded, whereby transmission of the message may be tracked. The invention may be implemented by using proprietary computer systems and applications to (a) encode the film as a streaming file, (b) create a Web page and insert the file thereon with templates, (c) adapt the Web page for viewing as an electronic mail message and (d) prepare the message for transmission to selected recipients.