Another type of electronic mailing list is a discussion list, in which any subscriber may post. On a discussion list, a subscriber uses the mailing list to send messages to all the other subscribers, who may answer in similar fashion. Thus, actual discussion and information exchanges can happen. Mailing lists of this type are usually topic-oriented (for example, politics, scientific discussion, health problems, joke contests), and the topic may range from extremely narrow to "whatever you think could interest us". In this they are similar to Usenet newsgroups, another form of discussion group that may have an aversion to off-topic messages.
Push marketing is a proactive technique that enables e-marketers to "push" their product/service information to Web visitors or shoppers without their requesting it. Banner advertising, pop-up advertising, e-mail promotion, and spamming belong to push marketing. For instance, e-marketers can rent designated space from Internet service providers such as America Online or MSN for their banner or pop-up ads. Using animated graphics, appealing messages, and links, e-marketers try to lure visitors to their sites to buy their products or services. Many Internet users, however, find such ads annoying and employ software that blocks pop-ups and banner ads. <