E-mail addresses are crucial to the Internet community providing a quick, easy, cost effective means of contacting people to provide information or services. Along with the World Wide Web (WWW) e-mail is one of key building blocks of the Internet and arguably one of the reasons why the use of the Internet has grown so rapidly.

E-mailing provides the ability to market products or services to existing or potential customers at a low cost. This means a list of e-mail addresses are often regarded as a highly prized asset by website administrators. The amount of e-mail addresses in a company’s database can even increase the company’s value as it indicates the amount of potential customers it has. As a result many companies place a high degree of importance to the reliability (correctness) of gathered e-mail addresses.

The value of an e-mail address creates a need to check the ‘correctness’ of e-mail addresses entering into the company’s databases. Periodic checking of e-mail addresses in a database would reduce the amount of addresses that are no longer in use. These unused addresses increase as people change their e-mail address, often by changing their internet service provider.

This document investigates a number of methods to find the ‘correctness’ of an e-mail address, discusses how successful the methods found are likely to be and how feasible it would be to use them for commercial purposes.