bool IsValidEmail(string strIn)
{
    return Regex.IsMatch(strIn, @"^([\w-\.]+)@((\[[0-9]{1,3}\.[0-9]
    {1,3}\.[0-9]{1,3}\.)|(([\w-]+\.)+))([a-zA-Z]{2,4}|[0-9]{1,3})(\]?)$"); 
}

void OnLoggingIn(object sender, System.Web.UI.WebControls.LoginCancelEventArgs e)
{
    if (!IsValidEmail(log1.UserName))
    {
        log1.InstructionText = "e-mail address is invalid.";
        log1.InstructionTextStyle.ForeColor = System.Drawing.Color.Red;
        e.Cancel = true;
    }
    else
    {
        log1.InstructionText = String.Empty;
    }
}

void OnLoginError(object sender, EventArgs e)
{
    log1.HelpPageText = "logging in...";
    log1.PasswordRecoveryText = "Forgot your password?";
}

namespace Samples.AspNet.Controls
{
    public sealed class CustomLogin : Login
    {
        public CustomLogin() { }
        
        protected override void OnLoggingIn(LoginCancelEventArgs e)
        {   
            DropDownList list = (DropDownList)this.FindControl("domain");
            this.MembershipProvider = list.SelectedValue;
            base.OnLoggingIn(e);
        }
        
        protected override void CreateChildControls()
        {
            LayoutTemplate = new Temp1();
            base.CreateChildControls();
        }
    }
    
    public class Temp1 : ITemplate
    {
        void ITemplate.InstantiateIn(Control container)
        {
            TextBox UName = new TextBox();
            UName.ID = "UName";
            
            TextBox password = new TextBox();
            password.ID = "password";            
           
            CheckBox remember = new CheckBox();
            remember.ID = "RememberMe";
            remember.Text = "Don't forget me!";            
            
            Literal failure = new Literal();
            failure.ID = "FailureText";            
            
            DropDownList domain = new DropDownList();
            domain.ID = "Domain";
            domain.Items.Add(new ListItem("SqlMembers"));
            domain.Items.Add(new ListItem("SqlMembers2"));
            
                        Button submit = new Button();
            submit.CommandName = "login";
            submit.Text = "LOGIN";

            container.Controls.Add(new LiteralControl("UName:"));
            container.Controls.Add(UName);
            container.Controls.Add(new LiteralControl("
Password:"));
            container.Controls.Add(password);
            container.Controls.Add(new LiteralControl("
"));
            container.Controls.Add(remember);
            container.Controls.Add(new LiteralControl("
Domain:"));
            container.Controls.Add(domain);
            container.Controls.Add(new LiteralControl("
"));
            container.Controls.Add(failure);
            container.Controls.Add(new LiteralControl("
"));
            container.Controls.Add(submit);
        }
    }    
}