Note that this is just a list of the most commonly found problems -- it is not by any means a complete list of bugs/misfeatures. That can be approximated by searching the KB for "BUG:", but even that still doesn't list all the strangenesses that will occur from time to time.

8.1 How can I send a task request from CDO/MAPI?

You can't. The format of a task request is undocumented, and the last word from anyone at Microsoft was that the Outlook development team were not willing to give out any documentation. You _can_ send a plain task object -- set the message's Type to "IPM.Task" and it'll arrive as a task but without the accept/deny buttons. Task requests seem to arrive as two separate messages (one in the inbox, one in the tasks folder) linked in some manner; trying to simply set the type to "IPM.TaskRequest" results in Outlook crashing when it opens the messages. CDOLive has a partial list of the other properties that affect tasks. (see appendix)

You can send task requests from Outlook, however.

8.2 How can I read calendar information from MAPI?

This is also undocumented -- use CDO if at all possible. Alternatively, CDOLive has some documentation on the format of a calendar message. (see appendix).

8.3 Okay, how do I find the calendar folder at all from MAPI?

See KB 171670

8.4 How can I read someone else's calendar? I have permissions, but I can't read the messages as AppointmentItems. What about calendar entries in public folders?

(solution at end of this lot)

The documentation for AppointmentItems states that you can only read messages as AppointmentItems from a folder that you have got by using Folder f = session.GetDefaultFolder(CdoDefaultFolderCalendar). This is a restriction of CDO imposed for some unknown reason, and basically means you can only open calendar items for the primary user of the session.

If you can read someone else's mailbox, you can navigate to the calendar by looking for "Calendar" as the folder title or a folder with PR_CONTAINER_CLASS = "IPF.Appointment". Once there, you still need to somehow decode the calendar items -- using the documentation from CDOLive (see appendix) you can get at a lot of the information; recurrences aren't documented there, but it is possible to reverse-engineer the information. See http://www.deja.com/[ST_rn=ps]/getdoc.xp?AN=422943739&fmt=text for code I wrote to do this for recurrences. Note that the properties I use in that sample probably won't work on your system; you'll have to do named property stuff to get the actual values. Apologies for the inconvenience; but then again you'd have to use named properties anyway, so this is just more practise at finding the names for a given thing.. Also see KB 196508 for the KB article about this.

This also applies to calendar entries in public folders, only more so -- because a public folder is never the default calendar folder for someone, you can never read calendar entries from this directly.

An ingenious workaround (Thanks to Siegfried Weber for this tip) is to read the info on the Exchange Server and mailbox for the person in question from the GAL, use that to log into a dynamic profile pointing at that user, and then, because you're logged into that person's mailbox directly, you can use GetDefaultFolder. This will work, but will hit problems with either memory leaks (if you log in and out, see Q8.6) or just having an awful lot of open sessions. That said, it's by far the easiest way to get this stuff working.

8.5 How do I find all appointments/meetings between given dates?

Here's a code fragment to do this:

  ' s is a session that's been logged in.
  Dim f As MAPI.Folder
  Set f = s.GetDefaultFolder(CdoDefaultFolderCalendar)
  Dim ms As MAPI.Messages
  Set ms = f.Messages
  Dim fi As MAPI.MessageFilter
  Set fi = ms.Filter
  With fi
    Dim fs As MAPI.Fields
    Set fs = fi.Fields
    With fs
      Dim f1 As MAPI.Field
      Set f1 = .Add(CdoPR_START_DATE, #11/6/1998#)
      Set f1 = .Add(CdoPR_END_DATE, #11/2/1998#)
    End With
 End With
 ' now loop over `ms' using getfirst/getnext/whatever.

8.6 Why does my code leak memory?

There's a leak in the login/out code in MAPI (and thus CDO): See KB 215463 (leak in login code), 171427 (leak in CDO1.1 (1.2?)) folder handling code), 188958 (general survey of ways your MAPI code may not be freeing things up).

If you're using CDO or Outlook by using #import, see KB 231872 -- there's a leak in the code #import generates.

Workarounds for this:

1. Don't log in and out any more than you have to -- log in at the start of your program, and cache the session object so you stay logged in.
2. Make sure your program finishes every so often; when it exits, the leaked memory goes away with it.

8.7 How do I access custom properties in CDO? I get MAPI_E_NOT_FOUND when I try and read them.

There's a peculiarity in the way CDO decodes the propsetIDs; see KB 195656.

8.8 Why do my custom properties disappear from recurring meetings?

Because instances of recurring meetings aren't "real" messages -- CDO creates fake instances internally and stores them as attachments on the base meeting.

The properties don't actually disappear -- it's just that when you open one of these instances with CDO, CDO, for some peculiar reason, gives you a message that you can't get at these properties with.

Workaround as follows:

1. Open instance of meeting.
2. Get the Parent of the meeting's RecurrencePattern; this is the "base" message.
3. Loop over the table of attachments in the base meeting searching for an attachment where property 0x7ffb0000 | PT_FILETIME contains the same time as the start of the meeting instance (no timezone issues to worry about here).
4. Read the PR_ATTACHMENT_INDEX property from this row, and then do:

        hr = pMsgMAPI->OpenAttach(index, &IID_IMAPIProp, MAPI_BEST_ACCESS,
                                  (IAttach**)&pAttach1);                      
        LPMESSAGE pAttachMsg;
        hr = pAttach1->OpenProperty(PR_ATTACH_DATA_OBJ,&IID_IMessage,0,0,
                              (LPUNKNOWN*)&pAttachMsg);
   

   or use CDO, and code like:

        Set objAttachment = objMessage.Attachments.Items(1)
        Set objEmbeddedMsg = objAttachment.Source
   

5. Use MAPI named property stuff to read your property from pAttachMsg.

See http://www.geocities.com/djmitchella/recurringmeetings1.txt for a large explanation of how I came up with this particular solution, and why other possible workarounds won't work. (there are a _lot_ of bugs that you hit along the way..)

8.9 Why does my sent mail stay in the Outbox?

Three possiblities: if the mail arrives, then you need to set the PR_DELETE_AFTER_SUBMIT flag (assuming you're using extended MAPI). If you're using simple MAPI, you have to set the ForceDownload flag to true when you log in. If you're using CDO, you may need to use the DeliverNow method on the Session object -- this forces delivery of all currently pending messages.

8.10 When I read an attachment with the VB MAPI controls, I can only get the 8.3 version of the filename?

This is a limitation on those controls; you will have to use CDO to avoid it. To read the attachment in the first place, you need to use the AttachmentPathName property of the message; the attachment is stored in a temporary directory when you open the message.

8.11 Why do I get 2147483647 messages when I try and count the messages in a folder?

Because the Count property can lie to you. If you look at the documentation, it says that it may return &HFFFFFFF as the count of messages if it decides to not count things properly, and that's the number above.

8.12 Why does my advise sink miss the first event that passes it?

Because you have to "wake up" advise sinks by doing some sort of RPC event (bug). Opening a new folder and doing GetContentsTable() on the folder will do this. Also, see KB 190413 for the MS explanation of this.

8.13 Why can't I read calendar entries from _my_ calendar folder?

See KB Q196258 (version clash with CDO 1.1 being installed mistakenly with Outlook) and 194806 (now vanished, annoyingly, but it might come back; talks about the message class being wrong on occasions).

8.14 Why do I get MAPI_E_NOT_FOUND trying to read/write properties on messages?

See KB 179639 (survey of possible problems with CDO code giving this error) and 183094 (specifically with properties)

8.15 Why is it so complicated to do simple things in MAPI? Isn't there an easier way?

A lot of things may seem very complicated; reading a single property involves building a one-element array of Proptags, calling GetProps on the message, etc. There are a large set of helper functions provided for you (for instance HrGetOneProp will do the single-property read) -- try looking through the list in the documentation under Platform SDK|Messaging and Collaboration|Messaging API|Reference|MAPI Functions. The Exchange SDK also provides a lot of useful helper functions; look under Platform SDK|Messaging and Collaboration|Microsoft Exchange Server| Microsoft Exchange Server Programmers Guide|Reference|Functions|Function Descriptions. (for instance, a one-step function to get the GAL).

Also, as mentioned before, CDO provides much nicer wrappers for a lot of MAPI stuff; the helper functions tend to make raw MAPI code shorter, but not necessarily easier.

8.16 I found the ID for a property on messages -- but now I'm on a different server, the ID's changed. What gives?

A lot of the more obscure undocumented properties that make up messages use named properties -- these are properties accessed by passing a name and propsetID to the Exchange Server in question; the server then converts these into an ID and uses that ID to store them. If you move to another server, the ID corresponding to a particular name may change. To find the name for a particular ID, your easiest route is to use MDBView (see appendix A), open the message, find the property you're interested in in the property dialog, and use the NamesToIDs button. One trick to be aware of is that you'll probably get something along the lines of "*lppPropNames.Kind.IID = 34070" -- this means that the name is actually "0x8516" (ie a string, 0, x, hex representation of the number). Quite why things wind up this way is a mystery, but this is the way it goes.

To read from a named property using CDO, you need code like: Fields fs = message.Fields Field f = fs.Item("0x8516", propsetid) where the propsetID is got from the value from MDBView. See Q8.7, though, because CDO is a bit glitchy here.

Alternatively, look at http://www.cdolive.com/cdo10.htm where there's a big list of the names and propsetIDs for most of the properties you're every likely to need, and save yourself a lot of effort.

8.17 My MAPI application fails when I try and run it from an MTA thread and/or an ATL (D)COM server.

Threading in MAPI seems to have some issues -- in particular, when you call MAPIInitialize, it calls CoInitialize(NULL). If you've already called CoInitializeEx() with MTA threading, the MAPI call to plain CoInitialize will hit problems. This can happen with the boilerplate code that VC++ builds for ATL (D)COM servers if you select the wrong option in the wizards. (thanks to Didier Clabaut for this info).

Also, see KB 239785 for possible interaction problems with Outlook 97; fix is to upgrade to Outlook '98. (For reference, I haven't hit this problem myself and I'm in the situation this article describes.. I may just be lucky, though.)

8.18 What's with the HRESULTS I get in my C++ CDO errors? They don't make any sense?

The code that #import generates for CDO has a bug where the HRESULTs in the exceptions thrown are messed up -- see KB 235361 for a table of results, and search that table for the middle column matching hrFake where hrFake is calculated from the _com_error e as follows: HRESULT hrFake = e.WCode(); hrFake = hrFake & 0xffff; (I'm not sure what the +1000 stuff they talk about there is, to be honest; doing things this way works fine).

8.19 Why can't I open the messages I get in notifications to my Outlook extension?

(I don't know anything about this code, I'm just putting it in here because this is a reasonably common problem. Thanks to James B. at Microsoft for the source here; I'm just quoting directly from him.)

    --startquote--

  LPMDB lpStore = NULL;
  LPMESSAGE lpMessage = NULL;
  LPADRBOOK lpAddrBook = NULL;
  LPSPropValue lpProps = NULL;
  lpeecb->GetObject(&lpStore, (LPMAPIPROP*) &lpMessage);
  HrGetOneProp((LPMAPIPROP) lpMessage, PR_ENTRYID, &lpProps);
  LPSTR lpszEID = (LPSTR) new char[(lpProps->Value.bin.cb*2)+1];
  HexFromBin(lpProps->Value.bin.lpb, lpProps->Value.bin.cb, lpszEID);
  // Open the item inside the Outlook Object Model
  LPOUTLEXTCALLBACK lpoecb = NULL;
  try {
    _NameSpacePtr spMAPI =
             m_lpCEE->m_spApplication->GetNamespace("MAPI");
    _MailItemPtr spMyItem =
    spMAPI->GetItemFromID(lpszEID);
    delete[] lpszEID;
   // Do work with the item here
  } catch (_com_error) {
    ::MessageBox(NULL, "Unable to get the MailItem in OnDelivery", 
      "Error", MB_OK);
  }

8.20 Why do I get MAPI_E_NO_SUPPORT trying to open a calendar folder?

This is probably related to Outlook '98 -- see KB 194077.

8.21 What happens when I try mixing multi-threaded code and MAPI?

See KB 239096 (CDO glitch where it calls CoInitialize(NULL)) and 239853 (same thing wrt MAPI) for more information on this.

8.22 Why do I get CdoE_NO_SUPPORT when trying to log in?

See KB 244547 -- some versions of CDO.DLL are incorrectly labelled as being for both Win9x and NT, when they shouldn't be.

8.23 Why don't I get calendar items in my event script?

See KB 243387 -- which just says "yes, it does this" and doesn't give a workaround or suchlike.. See Q8.4 for more on this sort of thing.

  uses comobj;

  procedure CreateAnOutlookEmail;
  var
    OA , 
    NS , 
    MI , // MailItem
    FO ,
    MyUserProperty : variant ;
  begin

    OA := CreateOleObject('Outlook.Application') ;
    NS := OA.GetNameSpace('MAPI') ;


    // IDispatch(MI) := FO.Items.Add('IPM.Note');

    MI := OA.CreateItem(0) ;

    MI.To := 'user@domain.com' ;
    MI.Subject := 'Outlook EMail from Delphi' ;
    MI.Body := 'Bla bla bla' ;
    //  uncomment the next line if you need to add an attachment
      MI.Attachments.Add('c:\foo.txt', emptyparam, emptyparam, emptyparam) ; 
    MI.Send ;
  end;

  procedure SendMoreEmailFromDelphi;
  var
    OA : _DApplication ;
    NS : NameSpace ;
    MI : MailItem ;
  begin
    OA := CoApplication.Create ;
    NS := OA.GetNamespace('MAPI') ;
    NS.Logon('myProfile' , 'myPassword' , false , false ) ;
    MI := OA.CreateItem(olMailItem) as _DMailItem;
    MI.Recipients.Add('user@domain.com') ;
    MI.Subject := 'Mail From Delphi' ;
    MI.Body := 'Here is the body of the message' ;
    MI.Send ;
  end;