[c#] using c# .net libraries to check for IMAP messages from gmail servers

Another alternative: HigLabo

https://higlabo.codeplex.com/documentation

Good discussion: https://higlabo.codeplex.com/discussions/479250

//====Imap sample================================//
//You can set default value by Default property
ImapClient.Default.UserName = "your server name";
ImapClient cl = new ImapClient("your server name");
cl.UserName = "your name";
cl.Password = "pass";
cl.Ssl = false;
if (cl.Authenticate() == true)
{
    Int32 MailIndex = 1;
    //Get all folder
    List<ImapFolder> l = cl.GetAllFolders();
    ImapFolder rFolder = cl.SelectFolder("INBOX");
    MailMessage mg = cl.GetMessage(MailIndex);
}

//Delete selected mail from mailbox
ImapClient pop = new ImapClient("server name", 110, "user name", "pass");
pop.AuthenticateMode = Pop3AuthenticateMode.Pop;
Int64[] DeleteIndexList = new.....//It depend on your needs
cl.DeleteEMail(DeleteIndexList);

//Get unread message list from GMail
using (ImapClient cl = new ImapClient("imap.gmail.com")) 
{
    cl.Port = 993;
    cl.Ssl = true; 
    cl.UserName = "xxxxx";
    cl.Password = "yyyyy";
    var bl = cl.Authenticate();
    if (bl == true)
    {
        //Select folder
        ImapFolder folder = cl.SelectFolder("[Gmail]/All Mail");
        //Search Unread
        SearchResult list = cl.ExecuteSearch("UNSEEN UNDELETED");
        //Get all unread mail
        for (int i = 0; i < list.MailIndexList.Count; i++)
        {
            mg = cl.GetMessage(list.MailIndexList[i]);
        }
    }
    //Change mail read state as read
    cl.ExecuteStore(1, StoreItem.FlagsReplace, "UNSEEN")
}


//Create draft mail to mailbox
using (ImapClient cl = new ImapClient("imap.gmail.com")) 
{
    cl.Port = 993;
    cl.Ssl = true; 
    cl.UserName = "xxxxx";
    cl.Password = "yyyyy";
    var bl = cl.Authenticate();
    if (bl == true)
    {
        var smg = new SmtpMessage("from mail address", "to mail addres list"
            , "cc mail address list", "This is a test mail.", "Hi.It is my draft mail");
        cl.ExecuteAppend("GMail/Drafts", smg.GetDataText(), "\\Draft", DateTimeOffset.Now); 
    }
}

//Idle
using (var cl = new ImapClient("imap.gmail.com", 993, "user name", "pass"))
{
    cl.Ssl = true;
    cl.ReceiveTimeout = 10 * 60 * 1000;//10 minute
    if (cl.Authenticate() == true)
    {
        var l = cl.GetAllFolders();
        ImapFolder r = cl.SelectFolder("INBOX");
        //You must dispose ImapIdleCommand object
        using (var cm = cl.CreateImapIdleCommand()) Caution! Ensure dispose command object
        {
            //This handler is invoked when you receive a mesage from server
            cm.MessageReceived += (Object o, ImapIdleCommandMessageReceivedEventArgs e) =>
            {
                foreach (var mg in e.MessageList)
                {
                    String text = String.Format("Type is {0} Number is {1}", mg.MessageType, mg.Number);
                    Console.WriteLine(text);
                }
            };
            cl.ExecuteIdle(cm);
            while (true)
            {
                var line = Console.ReadLine();
                if (line == "done")
                {
                    cl.ExecuteDone(cm);
                    break;
                }
            }
        }
    }
}