Email Address Validation for ASP.NET

Solution 1:

Any script tags posted on an ASP.NET web form will cause your site to throw and unhandled exception.

You can use a asp regex validator to confirm input, just ensure you wrap your code behind method with a if(IsValid) clause in case your javascript is bypassed. If your client javascript is bypassed and script tags are posted to your asp.net form, asp.net will throw a unhandled exception.

You can use something like:

<asp:RegularExpressionValidator ID="regexEmailValid" runat="server" ValidationExpression="\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*" ControlToValidate="tbEmail" ErrorMessage="Invalid Email Format"></asp:RegularExpressionValidator>

Solution 2:

Here is a basic email validator I just created based on Simon Johnson's idea. It just needs the extra functionality of DNS lookup being added if it is required.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web.UI.WebControls;
using System.Text.RegularExpressions;
using System.Web.UI;

namespace CompanyName.Library.Web.Controls
{
    [ToolboxData("<{0}:EmailValidator runat=server></{0}:EmailValidator>")]
    public class EmailValidator : BaseValidator
    {

        protected override bool EvaluateIsValid()
        {
            string val = this.GetControlValidationValue(this.ControlToValidate);
            string pattern = @"^[a-z][a-z|0-9|]*([_][a-z|0-9]+)*([.][a-z|0-9]+([_][a-z|0-9]+)*)?@[a-z][a-z|0-9|]*\.([a-z][a-z|0-9]*(\.[a-z][a-z|0-9]*)?)$";
            Match match = Regex.Match(val.Trim(), pattern, RegexOptions.IgnoreCase);

            if (match.Success)
                return true;
            else
                return false;
        }

    }
}

Update: Please don't use the original Regex. Seek out a newer more complete sample.