Illicit e-mail marketing antedates legitimate e-mail marketing, since on the early Internet (see Arpanet) it was not permitted to use the medium for commercial purposes. As a result, marketers attempting to establish themselves as legitimate businesses in e-mail marketing have had an uphill battle, hampered also by criminal spam operations billing themselves as legitimate.
It is frequently difficult for observers to distinguish between legitimate and spam e-mail marketing. First off, spammers attempt to represent themselves as legitimate operators, obfuscating the issue. Second, direct-marketing political groups such as the U.S. Direct Marketing Association (DMA) have pressured legislatures to legalize activities which many Internet operators consider to be spamming, such as the sending of "opt-out" unsolicited commercial e-mail. Third, the sheer volume of spam e-mail has led some users to mistake legitimate commercial e-mail (for instance, a mailing list to which the user subscribed) for spam - especially when the two have a similar appearance, as when messages include HTML and flashy graphics.
Due to the volume of spam e-mail on the Internet, spam filters are essential to most users. Some marketers report that legitimate commercial e-mails frequently get caught by filters, and hidden; however, it is somewhat less common for e-mail users to complain that spam filters block legitimate mail.
End of Article - What is Direct Email Marketing Software?