Disadvantages of Email Marketing

Many companies use e-mail marketing to communicate with existing customers, but many other companies send unsolicited bulk e-mail, also known as spam.
Internet system administrators have always considered themselves responsible for dealing with "abuse of the net", but not "abuse on the net". That is, they will act quite vigorously against spam, but will leave issues such as libel or trademark infringement to the legal system. Most administrators possess a passionate dislike for spam, which they define as any unsolicited e-mail. Draconian measures—such as taking down a corporate website, with or without warning—are entirely normal responses to spamming. Typically, the terms of service in Internet companies' contracts permit such actions; therefore, the spammer often has no recourse.
Illicit e-mail marketing predates legitimate e-mail marketing. On the early Internet (i.e., 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 ones.
It is frequently difficult for observers to distinguish between legitimate and spam e-mail marketing. First, spammers attempt to represent themselves as legitimate operators. Second, direct-marketing political groups such as the United States Direct Marketing Association (DMA) have pressured legislatures to legalize activities that some Internet operators consider to be spamming, such as the sending of "opt-out" unsolicited commercial e-mail. Third, the sheer volume of spam has led some users to mistake legitimate commercial e-mail for spam. This situation arises when a user receives e-mail from a mailing list to which he/she subscribes. Additional confusion arises when both legitimate and spam messages have a similar appearance, as when messages include HTML and graphics.
One effective technique used by established email marketing companies is to require what is known as the "double opt-in" method of requiring a potential recipient to manually confirm their request for information by clicking a unique link which includes a unique identification code to confirm that the owner of the recipient email address has indeed requested the information. Responsible e-mail marketing and autoresponder companies use this double opt-in method to confirm each request before any information is sent out.
A report issued by the e-mail services company Return Path, as of mid-2008 e-mail deliverability is still an issue for legitimate marketers. According to the report, legitimate e-mail servers averaged a delivery rate of 56%; twenty percent of the messages were rejected, and eight percent were filtered.[5]
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-mail messages frequently get caught and hidden by filters; however, it is somewhat less common for e-mail users to complain that spam filters block legitimate mail.
Companies considering the use of an e-mail marketing program must make sure that their program does not violate spam laws such as the United States' Controlling the Assault of Non-Solicited Pornography and Marketing Act (CAN-SPAM),[6] the European Privacy and Electronic Communications Regulations 2003, or their Internet service provider's acceptable use policy. Even if a company adheres to the applicable laws, it can be blacklisted (e.g., on SPEWS) if Internet e-mail administrators determine that the company is sending spam.