Email Address Validation in C# (With and without Regex)

: 15620

Last Updated : 06/05/2022

Posted By :- vikas_jk

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).

Validate email address using regex in C#

When validating an email address using regex, you need to include namespace System.Text.RegularExpressions in your C# code, let's take a look at an example

using System;
using System.Text.RegularExpressions;				
public class Program
{
	public static void Main()
	{
		var EmailId1="test@gmail.com";
		var EmailId2= "test1212@com";
		
		string pattern = @"\A(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?)\Z";
		
		//check first string
	   if (Regex.IsMatch(EmailId1 , pattern))
	   {	
		   //if email is valid
		    Console.WriteLine(EmailId1+ " is a valid Email address ");
	   }
	   else
	   {
		    Console.WriteLine(EmailId1 + " is not a valid Email address");			
	   }

		//check second string
	   if (Regex.IsMatch(EmailId2 , pattern))
	   {		 
		   //print if email id is valid
		    Console.WriteLine(EmailId2+ " is Valid Email address ");
	   }
	   else
	   {
		   //print if email id is not valid
		    Console.WriteLine(EmailId2 + " is Not a Valid Email address");			
	   }
	}
}

Output:

test@gmail.com is a valid Email address 
test1212@com is Not a Valid Email address

In the above code, we are using given regular expression to validate email address

string pattern = @"\A(?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?)\Z";

Now, you can fine tune above code and add MX Record validation also using DNSClient Nuget package and MX Records of email using C# as below

// domain for example@gmail.com = gmail.com
public bool ValidateMXRecord(string domain, string mail)
{
            var lookup = new LookupClient(IPAddress.Parse("8.8.4.4"), IPAddress.Parse("8.8.8.8"));
            lookup.Timeout = TimeSpan.FromSeconds(5);
            var result = lookup.Query(domain, QueryType.MX);

            var records = result.Answers;

            if (records.Any())
            {
                return true;
            }
            else
            {
                return false;
            }
}

You might also like to read:

Verify email address exists or not? (With email id validation in C#)

Remote Validations in MVC (Check if Email id exists in database)

Validate email address using Data Annotation in MVC C# Model

We can also validate email address using EmailAddress data annotation in C# class, suppose here is my StudentModel.cs class

using System.ComponentModel.DataAnnotations;

namespace MVCValidateEmailAddress.Models
{
    public class StudentModel
    {
        public string Name { get; set; }

        [Required]
        // data annotation to validate email in C#
        [EmailAddress(ErrorMessage = "Enter valid Email address")]
        public string EmailAddress { get; set; }
    }
}

you need to include System.ComponentModel.DataAnnotations namespace in your C# class to use EmailAddress data annotation.

Now when using this ViewModel inside MVC view, we can have code like this

@model MVCValidateEmailAddress.Models.StudentModel
@{
    ViewBag.Title = "Home Page";
    Layout = null;
}
<!DOCTYPE html>
<html>
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>@ViewBag.Title - My ASP.NET Application</title>
    @Styles.Render("~/Content/css")
</head>
<body>
    <div class="container body-content">
        @using (Html.BeginForm())
        {
            <div class="form-group">
                @Html.LabelFor(m => m.Name)
                @Html.TextBoxFor(model => model.Name, new { @class = "form-control" })

            </div>

            <div class="form-group">
                @Html.LabelFor(m => m.EmailAddress)
                @Html.TextBoxFor(model => model.EmailAddress, new { @class = "form-control" })
                @Html.ValidationMessageFor(model => model.EmailAddress)
            </div>

            <button type="button" class="btn btn-success submit">Save</button>
        }
        </div>
    <script src="~/Scripts/jquery-1.10.2.js"></script>
    <script src="~/Scripts/jquery.validate.js"></script>
    <script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>

</body>
</html>

In the above code, we are using razor syntax to create html label using @Html.LabelFor() and Textbox using @Html.TextBoxFor()

With the help of @Html.ValidationMessageFor (model=>model.EmailAddress) we are showing validation error message from data annotation inside this html form.

As you can see we have referenced jQuery scripts <script src="~/Scripts/jquery-1.10.2.js"></script>,<script src="~/Scripts/jquery.validate.js"></script>, <script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>, it is required to refer these files in your HTML page in order to make data annotation work.

Just build and run your project in brower, you will see output as below