Function to validate email address

App.xaml

<Style x:Key="TokkriHeaderStyle" TargetType="ContentControl">
            <Setter Property="FontSize" Value="16"/>
            <Setter Property="FontWeight" Value="SemiBold"/>
            <Setter Property="Foreground" Value="{StaticResource TokkriTheme}"/>
            <Setter Property="Margin" Value="0,4,0,4"/>
            <Setter Property="HorizontalAlignment" Value="Left"/>
        </Style>
<Style x:Key="TokkriTextBox" TargetType="telerikPrimitives:RadTextBox">
            <Setter Property="HeaderStyle" Value="{StaticResource TokkriHeaderStyle}"/>
            <Setter Property="Height" Value="108"/>
            <Setter Property="VerticalAlignment" Value="Center"/>
            <Setter Property="Background" Value="WhiteSmoke"/>
            <Setter Property="Foreground" Value="Black"/>
        </Style>

MainPage.cs

private bool ValidateEmailID()
        {
            emailfield.ChangeValidationState(ValidationState.Validating, "validating");
            bool isValid = isValidEmail(emailfield.Text);
            if (isValid)
            {
                emailfield.ChangeValidationState(ValidationState.Valid, "great!");
            }
            else
            {
                emailfield.ChangeValidationState(ValidationState.Invalid, "Invalid email address!");
            }
            return isValid;
        }

public static bool isValidEmail(string inputEmail)
        {
            string strRegex = @"^([a-zA-Z0-9_\-\.]+)@((\[[0-9]{1,3}" +
                  @"\.[0-9]{1,3}\.[0-9]{1,3}\.)|(([a-zA-Z0-9\-]+\" +
                  @".)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$";
            Regex re = new Regex(strRegex);
            if (re.IsMatch(inputEmail))
                return (true);
            else
                return (false);
        }

Mainpage.xaml

<telerikPrimitives:RadTextBox Name="emailfield" Header="EMAIL" Style="{StaticResource TokkriTextBox}"/>