C#

Microsoft.Exchange.WebServices.Data.ServiceResponseException: 
     When making a request as an account that does not have a mailbox, you must specify the mailbox primary SMTP address for any distinguished folder Ids.

public class ExchangeTask
{
   ExchangeService myService = new ExchangeService(ExchangeVersion.Exchange2007_SP1);
	public ExchangeTask()
	{
         ServicePointManager.ServerCertificateValidationCallback = delegate(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
        {
        // Trust all certificates. WARNING: Don't do this in production code!
            return true;
        };
        myService.UseDefaultCredentials = true;
        myService.AutodiscoverUrl(EmailAddressToFind);
        ServiceURL = myService.Url.ToString();
    }

    public void SendTask()
    {
        Task myTask = new Task(myService);
        
        myTask.Body = "This is a reminder task that has automatically been set by ExchangeWebservices";
        myTask.DueDate = DateTime.Now;
        myTask.ReminderDueBy = DateTime.Now;
        myTask.StartDate = DateTime.Now;
        myTask.Subject = "Event Reminder Task";
        myTask.Save();
    }