13.3. Verifying email addresses using pattern matching
13.3.1. Pattern matching and emailing
In the early days of Web design and businesses, one of the daily problems that the network administrators faced was the increasing amount of invalid email addresses. Unlike other information, an email address has to be precise and complete so that mail can be delivered properly. Just imagine how many times you have put spaces, commas, semi-colons, and more than one “@” symbol in an email address. Before the advent of so-called fourth-generation browser software, e.g., IE4+ and NS4+, to pick up these errors and validate an email address was a difficult problem.
One effective and convenient way of validating an email address is by means of pattern matching. ...