Email Address Validation for ASP.NET

What do you use to validate an email address on a ASP.NET form. I want to make sure that it contains no XSS exploits.

This is ASP.NET 1.1

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>

Validate Email Address using Regular Expression Validator in ASP , The RegularExpressionValidator has the following properties. ControlToValidate – ID of the TextBox control to be validated. ValidationExpression – The Regular Expression for validating the TextBox content. In this example, the Email Address. ErrorMessage – The Error Message to be displayed when Validation fails. How to validate email id exist or not using c#.net validation for Email Ids How to use multiple client side validation for both email and password in ASP.NET C# ?

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.

Email Validation, Which Validator is used to validate the email address in C#? The best way to confirm an email address is to email the user, and get the user to reply by clicking on a link to validate that they have recieved the email (the way most sign-up systems work).

You can use a RegularExpression validator. The ValidationExpression property has a button you can press in Visual Studio's property's panel that gets lists a lot of useful expressions. The one they use for email addresses is:

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

Best Way to Validate Email Addresses in C#, domain name must start with “A-Za-z0-9-“, follow by first level Tld (.com, . The above email address feedback is the local part and net-informations.com is the domain name to which the email message will be sent . Here we are going to implement a regular expression pattern to validate email address. A regular expression is a pattern describing a certain amount of text.

Validating that it is a real email address is much harder.

The regex to confirm the syntax is correct can be very long (see http://www.regular-expressions.info/email.html for example). The best way to confirm an email address is to email the user, and get the user to reply by clicking on a link to validate that they have recieved the email (the way most sign-up systems work).

How to validate email address with regular expression – Mkyong.com, To verify that the email address is valid, the IsValidEmail method calls the Regex. It merely determines whether its format is valid for an email address. In addition​, the See also .NET Framework Regular Expressions  In this chapter, I explained how to use Data Annotation for validating input field in ASP.NET MVC 5. I also explained how to add custom validation rule in DataAnnotation. In the next chapter, you will learn Remote Validation in ASP.NET MVC. Remote Validation checks user input field instantly when the focus jumps out from input control.

In our code we have a specific validator inherited from the BaseValidator class.

This class does the following:

  1. Validates the e-mail address against a regular expression.
  2. Does a lookup on the MX record for the domain to make sure there is at least a server to deliver to.

This is the closest you can get to validation without actually sending the person an e-mail confirmation link.

Valid email address format, An email address is a string of a subset of ASCII characters separated into two parts by an @ symbol. The example defines an IsValidEmail method, which returns true if the string contains a valid email address and false if it does not, but takes no other action. To verify that the email address is valid, the IsValidEmail method calls the Regex.Replace(String, String, MatchEvaluator) method with the (@)(.+)$ regular expression pattern to separate the domain name from the email address.

How to verify that strings are in valid email format, try the below pattern. Hide Copy Code. string strPattern = @"\w+([-+.]\w+)*@\w+([-​.]\w+)*\.\w+([-.]\w+)*";. Checks whether the specified value is valid with respect to the current validation attribute. (Inherited from ValidationAttribute) IsDefaultAttribute() When overridden in a derived class, indicates whether the value of this instance is the default value for the derived class. (Inherited from Attribute) IsValid(Object)

Email Address Validation - ASP-NET Information, RegEx is a popular method of validating emails, but there is a better method validation methods automatically across all platforms (forms, asp.net etc. Net.​Mail.MailAddress class. To determine whether an email address is  It is very common part of the web-application to include email address, and for this we require to validate if email address is correct and acceptable to save in database or not, so in this post, I have explained how we can validate email address in C# using regex and without using regex also (using data annotation in mvc).

how to validate email address using asp.net?, Email Id validation in asp.net with Regular Expression. ASP.Net Tutorials.Duration: 2:25 Posted: Apr 25, 2017 Use that. It is possible to validate an e-mail address with a regex, but it is a long regex. Very long. And in the end you will be none the wiser. You'll only know that the format is valid, but you still don't know if it's an active e-mail address. The only way to find out, is by sending a confirmation e-mail.

Comments
  • He said it's ASP.NET 1.1, are validation controls supported in that version?
  • RegularExpressionValidators are available in ASP.NET 1.1 msdn.microsoft.com/en-us/library/eahwtc9e%28v=VS.71%29.aspx
  • I use this expression, but strangely it seems to allow empty emails......? I had to add a required field validator as well.
  • Please keep in mind that this excludes some valid e-mail addresses.
  • Please keep in mind that this excludes some valid e-mail addresses.
  • The | in the character class [a-z|0-9|] seems wrong. Are you aware that this will match the | character and not work as an alternative? Besides this has failed for my e-mail address (test with 1a@a.com or a@1.com), so it's obviously wrong.
  • Please keep in mind that this excludes some valid e-mail addresses.
  • Where is this button? Can't find it in Visual Studio 2017 at least.
  • How do you find this works in practice. Don't you find doing a DNS lookup is a touch slow?