In 2002 the European Union introduced the Directive on Privacy and Electronic Communications. Article 13 of the Directive prohibits the use of email addresses for marketing purposes. The Directive establishes the opt-in regime, where unsolicited emails may be sent only with prior agreement of the recipient.
The directive has since been incorporated into the laws of member states. In the UK it is covered under the Privacy and Electronic Communications (EC Directive) Regulations 2003 and applies to all organisations that send out marketing by some form of electronic communication.
The CAN-SPAM Act of 2003 authorizes a US $16,000 penalty per violation for spamming each individual recipient. Therefore, many commercial email marketers within the United States utilize a service or special software to ensure compliance with the Act. A variety of older systems exist that do not ensure compliance with the Act. To comply with the Act's regulation of commercial email, services typically require users to authenticate their return address and include a valid physical address, provide a one-click unsubscribe feature, and prohibit importing lists of purchased addresses that may not have given valid permission.
In addition to satisfying legal requirements, email service providers (ESPs) began to help customers establish and manage their own email marketing campaigns. The service providers supply email templates and general best practices, as well as methods for handling subscriptions and cancellations automatically. Some ESPs will provide insight/assistance with deliverability issues for major email providers. They also provide statistics pertaining to the number of messages received and opened, and whether the recipients clicked on any links within the messages.