.NET Mail Composer

using System;
using System.Windows.Forms;

namespace MailComposer
{
    static class Program
    {
        public static string UserId = "", Password = "", Host = "";
        public static string ReplyTo = "", DisplayName = "";
        public static string EmailLocation = "";
        public static int ProviderIndex;
        public static int Port = 587;
        public static ListBox Recipients;
        public static ListView Attachments;
        public static bool SecureConnection;

        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Recipients = new ListBox();
            Attachments = new ListView();
            Application.Run(new frmComposer());
        }

        public static bool ValidateEmail(string Email)
        {
            if ((Email.IndexOf('@') != Email.LastIndexOf('@')) || Email.IndexOf('@') == -1) return false;

            if (Email[Email.IndexOf('@') + 1] == '.') return false;

            if ((Email.LastIndexOf(".") == Email.Length - 1) || Email.LastIndexOf(".") == -1) return false;

            if (Email.Contains(" ") || Email.Contains("\\") || Email.Contains("/") || Email.Contains("*") || Email.Contains(";")) return false;

            return true;
        }
    }
}