validating an e-mail address entry

Does anyone know of a way to validate an e-mail address that was entered and submitted from a form? I would like to trap invalid syntax. Perhaps there exists a script that does just that? I assume valid syntax is the following: One or more characters before the @ sign, followed by an optional '[', then any number of letters, numbers, dashes or periods (valid domain/IP characters) ending in a period and then 2 or 3 letters (for domain suffixes) or 1 to 3 numbers (for IP addresses). An ending bracket is also allowed as it is valid syntax to have an email address like: user@[255.255.255.0]. Thanks, Don