Email Validation of illegal characters

[brosseaa]

Does anyone have any code that validation with an email submitted is valid (checks for invalid characters, at least 1 @ sign and perhaps ',' delimited where there are multiple email addresses?
Also, how do you check for a string of characters within a string? I tried using the match() but am having little luck.
Any suggestions PLEASE!!!

[acoder]

Regular expressions are a good way of validating user input. See how to use them in JavaScript here.
Also see this link for a possible email matching regular expression.