Axiom 1: If you're going to gather information on your users, make sure it's valid information.
If you're going to use FORMs to collect your user's information, it is important that you validate this information. Validation can be done in one of two ways, through client-side validation (i.e. JavaScript) or through server-side validation (ASP).
If you want to validate your user's email you need to check for a few things. The @ symbol, at least one period, at least one character before the @ symbol, at least one after before the period, and at least one after the period. Here are two server-side scripts which will help you validate email!
You can also validate email through client-side validation using JavaScript. Here is an article discussing that approach:Ian Stallings JScript/Regular Expression Email Validation Routine
Ben Durbin's Email Validation Routine
Joao Vieira's Email Validation Routine
Form Validation with JavaScript
Happy Programming!