E-mail marketing is a form of direct marketing which uses electronic mail as a means of communicating commercial or fundraising messages to an audience. In its broadest sense, every e-mail sent to a potential or current customer could be considered e-mail marketing. However, the term is usually used to refer to:

• sending e-mails with the purpose of enhancing the relationship of a merchant with its current or previous customers and to encourage customer loyalty and repeat business,

• sending e-mails with the purpose of acquiring new customers or convincing current customers to purchase something immediately,

• adding advertisements to e-mails sent by other companies to their customers, and

• sending e-mails over the Internet, as e-mail did and does exist outside the Internet (e.g., network e-mail and FIDO).

Researchers estimate that United States firms alone spent US$400 million on e-mail marketing in 2006.

Email Marketing Software refers to a computer application which provides the ability to send bulk email to target audiences. The intent is usually to send newsletters or promotional materials to opt-in lists of subscribers, although the software can be used to send unsolicited email. The software typically includes a database that stores contact information, campaign statistics, and message history. The interface provides features necessary to run an email campaign, such as message sending, contact entry, contact importing, and reporting. Software packages range in price from free, to about five hundred US dollars. Some companies charge a monthly fee. There are also enterprise solutions that can cost thousands of dollars a month to manage large enterprises mass marketing email campaigns.