Email validation in c#.net

using System.Text.RegularExpressions;
private void TxtEmail_Leave(object sender, EventArgs e)
        {
            if (TxtEmail.Text == "")
                return;
            Regex EMail = new Regex(@"^[a-zA-Z][\w\.-]{2,28}[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$");
            if (!EMail.IsMatch(TxtEmail.Text))
            {
                MessageBox.Show("Invalid Email ID", "Message", MessageBoxButtons.OK, MessageBoxIcon.Error);
                TxtEmail.Focus();
            }
        }