How To Set and Clear a CDO (1.x) MessageFilter via VC++

MORE INFORMATION

The following code sample shows how to activate, then deactivate a CDO (1.1, 1.2, 1.21) MessageFilter via Visual C++.

The key to successfully shutting or altering the MessageFilter is to be sure to destroy any reference that is made to any object related to the MessageFilter (also known as Folder:MessagesCollection:MessageFilter).

Code Sample:

   /**********************************************************/ 
   // MSGFILTER.CPP
   // -------------
   // This program demonstrates how the CDO (1.1, 1.2, 1.21)
   // MessageFilter works via VC++. This sample requires VC++
   // version 5.0 or higher.
   /**********************************************************/ 

   // TO DO: If you are using CDO (1.1) unremark the next line:
   // #import <olemsg32.dll> no_namespace

   // TO DO: If you are using CDO (1.2, 1.21) unremark the next line:
   // #import <cdo.dll> no_namespace

   #import <olemsg32.dll> no_namespace

   #include <assert.h>
   #include <stdio.h>
   #include <tchar.h>

   void dump_com_error(_com_error &e)
   {
       _tprintf(_T("Oops - hit an error!\n"));
       _tprintf(_T("\a\tCode = %08lx\n"), e.Error());
       _tprintf(_T("\a\tCode meaning = %s\n"), e.ErrorMessage());
       _bstr_t bstrSource(e.Source());
       _bstr_t bstrDescription(e.Description());
       _tprintf(_T("\a\tSource = %s\n"), (LPCTSTR) bstrSource);
       _tprintf(_T("\a\tDescription = %s\n"), (LPCTSTR) bstrDescription);
    }

   // If this is placed in the scope of the smart pointers, they must be
   // explicitly Release(d) before CoUninitialize() is called.  If any
   // reference count is non-zero, a protection fault will occur.
   struct StartOle {
      StartOle() { CoInitialize(NULL); }
      ~StartOle() { CoUninitialize(); }
   } _inst_StartOle;

   void main()
   {
   try
      {
          // Uncomment one of the next two lines of code as appropriate:
          // Create a MAPI.Session pointer with CDO (1.1)
          // SessionPtr pSession("MAPI.Session");
          // or Create a MAPI.Session pointer with CDO (1.2, 1.21)
          // _SessionPtr pSession("MAPI.Session");

          // Logon using the specified profile
          pSession->Logon("YourValidProfileNameHere");

          // Create pointer to the Inbox Folder
          FolderPtr pFolder = pSession->Inbox;

          // Create pointer to the Messages Collection
          MessagesPtr pMessages = pFolder->Messages;

          // Get the first Message object before filter is applied
          MessagePtr pAMessage = pMessages->GetFirst();

          // Process contents of Folder
          while (pAMessage != NULL)
          {
              // Display Properties
              MessageBoxW (NULL,pAMessage->Subject.bstrVal,NULL,MB_OK);

              // Get next Message
              pAMessage = NULL;
              pAMessage = pMessages->GetNext();
          }

          // Destroy the reference to the to the Inbox, Messages
          // Collection, and Message then reaquire them
          pFolder = NULL;
          pMessages = NULL;
          pAMessage = NULL;

          // Aquire pointer to the Inbox Folder
          pFolder = pSession->Inbox;

          // Aquire pointer to the Messages Collection
          pMessages = pFolder->Messages;

          // Acquire pointer and set properties of the MessageFilter
          MessageFilterPtr pMsgFilt = pMessages->Filter;
          pMsgFilt->Unread = (bool)TRUE;

          // Get the first Message object after filter is applied
          pAMessage = pMessages->GetFirst();

          // Process contents of Folder
          while (pAMessage != NULL)
          {
              // Display Properties
              MessageBoxW (NULL,pAMessage->Subject.bstrVal,NULL,MB_OK);

              // Get next Message
              pAMessage = NULL;
              pAMessage = pMessages->GetNext();
          }

          // Destroy the reference to the Inbox, Messages Collection,
          // MessageFilter, and Message then reaquire them
          pFolder = NULL;
          pMessages = NULL;
          pMsgFilt = NULL;
          pAMessage = NULL;

          // GetFirst() without a filter in place
          // Aquire pointer to the Inbox Folder
          pFolder = pSession->Inbox;

          // Aquire pointer to the Messages Collection
          pMessages = pFolder->Messages;

          // Get the first Message object after filter is unapplied
          pAMessage = pMessages->GetFirst();

          // Process contents of Folder
          while (pAMessage != NULL)
          {
              // Display Properties
              MessageBoxW (NULL,pAMessage->Subject.bstrVal,NULL,MB_OK);

              // Get next Message
              pAMessage = NULL;
              pAMessage = pMessages->GetNext();
          }

          // Logoff of the MAPI Session
          pSession->Logoff();
      }
      catch (_com_error &e)
      {
          dump_com_error(e);
      }
   }