To validate email address on client side, we can use java script with regular expression.Java script can check the regular expression pattern for valid email address.Here’s a fairly common code sample from Rails Applications with some sort of authentication system: If you’re experienced at Regex, this seems simple. Sections 3.2.4 and 3.4.1 of the RFC go into the requirements on how an email address needs to be formatted and, well, there’s not much you can’t do in your email address when quotes or backslashes are involved.If (like me when I first saw this) you AREN’T experienced at Regex, it takes a while to parse. The local string (the part of the email address that comes before the @) can contain any of these characters: is a valid email address. For this reason, for a time I began running any email address against the following regular expression instead: Simple, right? This is often the most I do and, when paired with a confirmation field for the email address on your registration form, can alleviate most problems with user error.Dim idn = New Idn Mapping 'Pull out and process domain name (throws Argument Exception on invalid) Dim domain Name As String = idn. The ending quotation mark must not be preceded by a backslash character (\).
At this point, why keep parsing email addresses for their format?A complex regex validation on the email address doesn’t introduce an additional solution, it introduces an additional problem.