E-mail marketing is a great way to communicate with your customers.

• 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 is expanding to text messages and other forms of communication.

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

Advantages

E-mail marketing is popular for several reasons:

• A mailing list provides the ability to distribute information to a wide range of specific, potential customers at a relatively low cost.
• Compared to other media investments such as direct mail or printed, e-mail is less expensive.
• An exact can be tracked ("track to basket") and has proven to be high when done properly. E-mail marketing is often reported as second only to search marketing as the most effective online marketing tactic.
• The delivery time for an e-mail message is short (i.e., seconds or minutes) as compared to a mailed advertisement (i.e., one or more days).
• An advertiser is able to "push" the message to its audience, as opposed to website-based advertising, which relies on a customer to visit that website.
• E-mail messages are easy to track. An advertiser can track users via autoresponders, web bugs, unsubscribe requests, read receipts, etc. These mechanisms can be used to measure open rates, positive or negative responses, and to correlate sales with marketing.
• Advertisers can generate repeat business affordably and automatically.
• Advertisers can reach substantial numbers of e-mail subscribers who have opted in (i.e., consented) to receive e-mail communications on subjects of interest to them.
• Over half of Internet users check or send e-mail on a typical day.
• Specific types of interaction with messages can trigger (1) other messages to be delivered automatically, or (2) other events, such as updating the profile of the recipient to indicate a specific interest category.
• E-mail marketing is paper-free (i.e., "green").

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.

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.

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 and entering a unique code identifier 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.

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, 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.

Opt-in e-mail advertising

Opt-in e-mail advertising, or permission marketing, is a method of advertising via e-mail where the recipient of the advertisement has consented to receive it. This method is one of several developed by marketers to eliminate the disadvantages of e-mail marketing.

Ideally, opt-in e-mail advertisements will be more personal and relevant to the consumer than untargeted advertisements.

A common example of permission marketing is a newsletter sent to an advertising firm's customers. Such newsletters inform customers of upcoming events or promotions, or new products. In this type of advertising, a company that wants to send a newsletter to their customers may ask them at the point of purchase if they would like to receive the newsletter.

With a foundation of opted-in contact information stored in their database, marketers can send out promotional materials automatically. They can also segment their promotions to specific market segments.

This can boost your sales significantly.