How to get new mail using VS office tool

Question

I'm writing an outlook addin office VS 2010 Office tools.

Here I find a way to list of unread emails from Inbox, but I want to process only new mails.

What I'm trying to do is - when an email comes with subject containing "my project", it should create a task. Here is my code

void Application_NewMail()
    {
        string filter = "my project";

        Outlook.NameSpace outlookNameSpace = this.Application.GetNamespace("MAPI");
        Outlook.MAPIFolder inbox = outlookNameSpace.GetDefaultFolder(
            Microsoft.Office.Interop.Outlook.
            OlDefaultFolders.olFolderInbox);

        Outlook.Items items = inbox.Items.Restrict("[Unread] = true");

        foreach (Outlook.MailItem mail in items)
        {
            if (mail.MessageClass == "IPM.Note" &&
                mail.Subject.ToUpper().Contains(filter.ToUpper()))
            {
                CreateTask(mail);                   
            }
        }
    }

    private void CreateTask(Outlook.MailItem mail)
    {
        Outlook.TaskItem task = new Outlook.TaskItem();
        task.Subject = mail.Subject;
        task.Body = mail.Body;
        task.Save();
    }