Check if input in textbox is email

Question

I am trying to validate if the userinput is an email adress (adding a member to database).

The user will enter data in TextBox, when the validating event gets called; I want to check if the input is a valid email adress. So consisting of atleast an @ and a dot(.) in the string.

Is there any way to do this through code, or perhaps with a Mask from the MaskedTextbox?

look up a Regex for validation emails, you should be easily able to find those — x4rf41, Jan 14 '14 at 20:57
possible duplicate of [email validation in a c# winforms application](http://stackoverflow.com/questions/1199413/email-validation-in-a-c-sharp-winforms-application) — Liam, Jan 21 '15 at 09:07

score 14 · Accepted Answer · edited May 23 '17 at 12:17

14

Don't bother with Regex. It's a Bad Idea.

I normally never use exceptions to control flow in the program, but personally, in this instance, I prefer to let the experts who created the MailAddress class do the work for me:

try
{
    var test = new MailAddress("");
}
catch (FormatException ex)
{
    // wrong format for email
}

edited May 23 '17 at 12:17

Community

1
1

answered Jan 14 '14 at 21:01

Grant Winney

65,241
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+1 for mentioning the `MailAddress` class. I had completely forgotten about it. – Brian Jan 14 '14 at 21:05
1

Holy hell that `Regex` is a mess... lol. I am thinking I may have to delete my answer to this question since I _suggested_ using a `Regex` in the first place. – Brian Jan 14 '14 at 21:35
I don't know why but this method doesn't work when you enter a mail like this : mail@mail --> this mail is valid using this way but invalid because it doesn't contain a domain. – HinoHara Mar 30 '15 at 18:07

score 4 · Answer 2 · answered Jan 14 '14 at 21:03

4

Do not use a regular expression, it misses so many cases it's not even funny, and besides smarter people that us have come before to solve this problem.

using System.ComponentModel.DataAnnotations;

public class TestModel{
    [EmailAddress]
    public string Email { get; set; }
}

answered Jan 14 '14 at 21:03

siva.k

1,344
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This should be the top answer. It builds email validation right into the form, rendered with @Html.ValidationMessageFor(m => m.Email) – SeanMC Sep 25 '17 at 19:10

score 2 · Answer 3 · answered Jan 14 '14 at 20:57

Regex for simple email match:

@"\b[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b"

Regex for RFC 2822 standard email match:

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

score 1 · Answer 4 · answered Jan 14 '14 at 20:58

See: How to: Verify that Strings Are in Valid Email Format - MSDN

The Regex you are looking should be:

"^(?("")(""[^""]+?""@)|(([0-9a-z]((\.(?!\.))|[-!#\$%&'\*\+/=\?\^`\{\}\|~\w])*)(?<=[0-9a-z])@)) 
(?(\[)(\[(\d{1,3}\.){3}\d{1,3}\])|(([0-9a-z][-\w]*[0-9a-z]*\.)+[a-z0-9]{2,24}))$"

(From the same source)

Kervin Guzman · Answer 5 · 2017-01-15T02:04:49.450

1

I recommend you use this way and it's working well for me.

    Regex reg = new Regex(@"\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*");
    if (!reg.IsMatch(txtEmail.Text))
    {
        // Email is not valid
    }

edited Jan 15 '17 at 02:04

answered Jan 09 '17 at 15:59

Kervin Guzman

131
1
5

1

Please provide enough details for answering the question... The OP mentioned that the data comes from a `TextBox`, the validation event is called and it should match a string with `atleast an @ and a dot(.)`. How does your code fulfill these requirements and where are your `isValid` and `UserMessage` variables used in order to accomplish the OP's goal? – CPHPython Jan 09 '17 at 16:31

Brian · Answer 6 · 2014-01-14T21:04:56.217

I suggest that you use a Regular Expression like:

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

To validate the input of your textbox.

Example code:

private void button1_Click(object sender, EventArgs e)
{
   Regex emailRegex = new Regex(@"[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?
                                ^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+
                                [a-z0-9](?:[a-z0-9-]*[a-z0-9])?");

   if (emailRegex.IsMatch(textBox1.Text))
   {
      MessageBox.Show(textBox1.Text + "matches the expected format.", "Attention"); 
   }
}

Edit: I found a better, more comprehensive Regex.

Check if input in textbox is email

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