Historically, it has been difficult to measure the effectiveness of marketing campaigns because target markets cannot be adequately defined. Email marketing carries the benefit of allowing marketers to identify returns on investment and measure and improve efficiency. Email marketing allows marketers to see feedback from users in real time, and to monitor how effective their campaign is in achieving market penetration, revealing a communication channel's scope. At the same time, however, it also means that the more personal nature of certain advertising methods, such as television advertisements, cannot be captured.
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. <