ASP.NET email validator regex

Question

Does anyone know what the regex used by the email validator in ASP.NET is?

Answer 1

Here is the regex for the Internet Email Address using the RegularExpressionValidator in .NET

\w+([-+.']\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*

By the way if you put a RegularExpressionValidator on the page and go to the design view there is a ValidationExpression field that you can use to choose from a list of expressions provided by .NET. Once you choose the expression you want there is a Validation expression: textbox that holds the regex used for the validator

Answer 2

I don't validate email address format anymore (Ok I check to make sure there is an at sign and a period after that). The reason for this is what says the correctly formatted address is even their email? You should be sending them an email and asking them to click a link or verify a code. This is the only real way to validate an email address is valid and that a person is actually able to recieve email.

Answer 3

E-mail addresses are very difficult to verify correctly with a mere regex. Here is a pretty scary regex that supposedly implements RFC822, chapter 6, the specification of valid e-mail addresses.

Not really an answer, but maybe related to what you're trying to accomplish.

Answer 4

We can use RegularExpressionValidator to validate email address format. You need to specify the regular expression in ValidationExpression property of RegularExpressionValidator. So it will look like

 <asp:RegularExpressionValidator ID="validateEmail"    
  runat="server" ErrorMessage="Invalid email."
  ControlToValidate="txtEmail" 
  ValidationExpression="^([\w\.\-]+)@([\w\-]+)((\.(\w){2,3})+)$" />

Also in event handler of button or link you need to check !Page.IsValid. Check sample code here : sample code

Also if you don't want to use RegularExpressionValidator you can write simple validate method and in that method usinf RegEx class of System.Text.RegularExpressions namespace.

Check example:

example

Answer 5

For regex, I first look at this web site: RegExLib.com

Answer 6

Apart from the client side validation with a Validator, I also recommend doing server side validation as well.

bool isValidEmail(string input)
{
    try
    {
        var email = new System.Net.Mail.MailAddress(input);
        return true;
    }
    catch
    {
        return false;
    }
}