public void EmailAppointmentCancellation(string _user, string _password, string _smtpserver)
        {

            //Send the calendar message to the attendee

            MailMessage loMsg = new MailMessage();
            AlternateView loTextView;
            AlternateView loHTMLView;
            AlternateView loCalendarView;
            SmtpClient loSMTPServer = new SmtpClient();

            // Set up the different mime types contained in the message
            System.Net.Mime.ContentType loTextType = new global::System.Net.Mime.ContentType("text/plain");
            System.Net.Mime.ContentType loHTMLType = new global::System.Net.Mime.ContentType("text/html");
            //System.Net.Mime.ContentType loCalendarType = new global::System.Net.Mime.ContentType("text/calendar;method=CANCEL");
            System.Net.Mime.ContentType loCalendarType = new global::System.Net.Mime.ContentType("text/calendar");

            //Add parameters to the calendar header
            loCalendarType.Parameters.Add("method", "CANCEL");
            loCalendarType.Parameters.Add("name", "meeting.ics");

            //Create message body parts
            loTextView = AlternateView.CreateAlternateViewFromString(BodyText(), loTextType);
            loMsg.AlternateViews.Add(loTextView);


            loHTMLView = AlternateView.CreateAlternateViewFromString(BodyHTML(), loHTMLType);
            loMsg.AlternateViews.Add(loHTMLView);

            loCalendarView = AlternateView.CreateAlternateViewFromString(VCalendarCancellation(), loCalendarType);
            loCalendarView.TransferEncoding = System.Net.Mime.TransferEncoding.SevenBit;
            loMsg.AlternateViews.Add(loCalendarView);

            //Adress the message
            loMsg.From = new System.Net.Mail.MailAddress(OrganizerEmail);
            loMsg.To.Add(new System.Net.Mail.MailAddress(AttendeeEmail));
            loMsg.Subject = Subject;


            System.Net.NetworkCredential _crenditials
                = new System.Net.NetworkCredential(_user, _password);

            //SmtpClient.Crenditals 
            loSMTPServer.Host = _smtpserver;
            loSMTPServer.Credentials = _crenditials;

            // Send the message
            loSMTPServer.DeliveryMethod = SmtpDeliveryMethod.Network;
            loSMTPServer.Send(loMsg);
        }
        public void EmailAppointmentInvitationV2(string _user, string _password,
            string _smtpserver, int _port, string _useEncryption)
        {
            
            //Send the calendar message to the attendee
            MailMessage loMsg = new MailMessage();
            AlternateView loTextView;
            AlternateView loHTMLView;
            AlternateView loCalendarView;
            SmtpClient loSMTPServer = new SmtpClient();

            // Set up the different mime types contained in the message
            System.Net.Mime.ContentType loTextType = new global::System.Net.Mime.ContentType("text/plain");
            System.Net.Mime.ContentType loHTMLType = new global::System.Net.Mime.ContentType("text/html");
            System.Net.Mime.ContentType loCalendarType = new global::System.Net.Mime.ContentType("text/calendar");

            //Add parameters to the calendar header
            loCalendarType.Parameters.Add("method", "REQUEST");
            loCalendarType.Parameters.Add("name", "meeting.ics");


            //Create message body parts
            loTextView = AlternateView.CreateAlternateViewFromString(BodyText(), loTextType);
            loMsg.AlternateViews.Add(loTextView);

            loHTMLView = AlternateView.CreateAlternateViewFromString(BodyHTML(), loHTMLType);
            loMsg.AlternateViews.Add(loHTMLView);

            loCalendarView = AlternateView.CreateAlternateViewFromString(VCalendarInvitation(), loCalendarType);
            loCalendarView.TransferEncoding = System.Net.Mime.TransferEncoding.SevenBit;
            loMsg.AlternateViews.Add(loCalendarView);

            //Adress the message
            loMsg.From = new System.Net.Mail.MailAddress(OrganizerEmail);
            loMsg.To.Add(new System.Net.Mail.MailAddress(AttendeeEmail));
            loMsg.Subject = Subject;

            loMsg.IsBodyHtml = true;

            System.Net.NetworkCredential _crenditials
                = new System.Net.NetworkCredential(_user, _password);

            //SmtpClient.Crenditals 
            loSMTPServer.Host = _smtpserver;
            loSMTPServer.Credentials = _crenditials;

            if (_useEncryption == "T")
            {
                loSMTPServer.EnableSsl = true;
            }

            if (_port > 0)
            {
                loSMTPServer.Port = _port;
            }

            loMsg.Body = "This is the body";
            // Send the message
            loSMTPServer.DeliveryMethod = SmtpDeliveryMethod.Network;
            loSMTPServer.Send(loMsg);
        }