Disadvantages

• Many companies use e-mail marketing to communicate with existing customers, but many other companies send unsolicited bulk e-mail, also known as spam.
• Illicit e-mail marketing antedates legitimate e-mail marketing, since on the early Internet it was not permitted to use the medium for commercial purposes.
• It is frequently difficult for observers to distinguish between legitimate and spam e-mail marketing.
• 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.
• It is somewhat less common for e-mail users to complain that spam filters block legitimate mail.