Bulk email, also known as "Spam", is an email marketing technique where a large number of emails are sent to people who did not request and probably have no interest in receiving email promotions. There are a number of difficulties involved with this type of marketing. Beginning with complaints from the annoyed recipients, up to and including the emailer losing their hosting account. Most bulk emailers will lose hosting within a week of sending a spam campaign. Those who do it from their home or office may have their account closed by their internet access provider. 

Targeted email is sending emails to a specific group that will probably have an interest in the email their being send. An example would be; you have a web-site for Realtors in Florida. You then email all the Realtors within Florida to promote that website. Rather than send emails to millions of uninterested recipients, your targeting a specific group. By doing this, you greatly increase your chances of a successful email campaign. Responsible users of lists will make sure that the recipients do not receive an excessive amount of email, or receive repeated email offers from the same source, and that the email offers they do receive are appropriate and of good quality -- that way, they will stay on the list for a longer time period.    

Although some people will build their lists through their websites, it is frequently done separately through something known as co-registration opt-out email campaigns. Co-registration means that the subscription to your email list is attached to another subscription that the person is interested in. They will sign up for your list as well, unless they uncheck the box to "opt-out". The danger in this method is that about one-third of the subscribers are there because they did not notice the opt-out box, so you do need to confirm each subscription to avoid accidentally spamming someone.

The Controlling the Assault of Non-Solicited Pornography and Marketing Act requires unsolicited commercial e-mail messages to be labeled (though not by a standard method) and to include opt-out instructions and the sender's physical address. It prohibits the use of deceptive subject lines and false headers in such messages. The FTC is authorized (but not required) to establish a "do-not-email" registry. State laws that require labels on unsolicited commercial e-mail or prohibit such messages entirely are pre-empted, although provisions merely addressing falsity and deception would remain in place. The CAN-SPAM Act takes effect on January 1, 2004.

The CAN-SPAM Act of 2003 was introduced by Senators Conrad R. Burns (R-MT) and Ron Wyden (D-OR) in April 2003, with minor changes from the previous year's version, S. 630 (2002). Two other bills (S. 1231 and S. 1293) were subsequently merged into it. The final version was approved by the Senate in November 2003 and by the House of Representatives in December 2003, and was signed into law by President Bush on December 16, 2003.