Email address validation using ASP.NET MVC data type attributes

Question

If you are using .NET Framework 4.5, the solution is to use EmailAddressAttribute which resides inside System.ComponentModel.DataAnnotations.

Your code should look similar to this:

[Display(Name = "Email address")]
[Required(ErrorMessage = "The email address is required")]
[EmailAddress(ErrorMessage = "Invalid Email Address")]
public string Email { get; set; }

Try Html.EditorFor helper method instead of Html.TextBoxFor.

You need to use RegularExpression attribute, something like this:

[RegularExpression("^[a-zA-Z0-9_\\.-]+@([a-zA-Z0-9-]+\\.)+[a-zA-Z]{2,6}$", ErrorMessage = "E-mail is not valid")]

And don't delete [Required] because [RegularExpression] doesn't affect empty fields.

if you aren't yet using .net 4.5:

/// <summary>
/// TODO: AFTER WE UPGRADE TO .NET 4.5 THIS WILL NO LONGER BE NECESSARY.
/// </summary>
public class EmailAnnotation : RegularExpressionAttribute
{
    static EmailAnnotation()
    {
        DataAnnotationsModelValidatorProvider.RegisterAdapter(typeof(EmailAnnotation), typeof(RegularExpressionAttributeAdapter));
    }

    /// <summary>
    /// from: http://stackoverflow.com/a/6893571/984463
    /// </summary>
    public EmailAnnotation()
        : base(@"^[\w!#$%&'*+\-/=?\^_`{|}~]+(\.[\w!#$%&'*+\-/=?\^_`{|}~]+)*"
            + "@"
            + @"((([\-\w]+\.)+[a-zA-Z]{2,4})|(([0-9]{1,3}\.){3}[0-9]{1,3}))$") { }

    public override string FormatErrorMessage(string name)
    {
        return "E-mail is not valid";
    }
}

Then you can do this:

    public class ContactEmailAddressDto
    {
        public int ContactId { get; set; }
        [Required]
        [Display(Name = "New Email Address")]
        [EmailAnnotation] //**<----- Nifty.**
        public string EmailAddressToAdd { get; set; }
    }

I use MVC 3. An example of email address property in one of my classes is:

[Display(Name = "Email address")]
[Required(ErrorMessage = "The email address is required")]
[Email(ErrorMessage = "The email address is not valid")]
public string Email { get; set; }

Remove the Required if the input is optional. No need for regular expressions although I have one which covers all of the options within an email address up to RFC 2822 level (it's very long).