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Posted 30 Mar 2002
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, 30 Mar 2002
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Usage of the simple MAPI API.

Sample Image - simplemapidotnet.jpg


As you know, .NET has SMTP email support built-in. For some special environments, the usage of e.g. the "Simple MAPI' API is prefered.


This API can be called like most other Win32 APIs with 'PInvoke'. By reading the MSDN documentation: Platform SDK - Simple MAPI and some hints from the C++ include header file MAPI.h, we can declare the calls in C# like:

[DllImport( "MAPI32.DLL", CharSet=CharSet.Ansi)]
private static extern int MAPIDeleteMail( IntPtr session, IntPtr winhandle,
                                      string id, int flags, int reserved );

For sending email with 'MAPISendMail', the structure 'MapiMessage' has to be filled with pointers to sub-structures like 'MapiRecipDesc'. For this, I used the System.Runtime.InteropServices.Marshal class:

Marshal.SizeOf(), Marshal.AllocHGlobal(),
Marshal.StructureToPtr(), Marshal.PtrToStructure(),
Marshal.DestroyStructure(), Marshal.FreeHGlobal()

Most SimpleMAPI functions are 'wrapped' in a handy class (MapiApi.cs):

public class Mapi
  // Session
  public bool Logon( IntPtr winhandle )
  public void Reset()
  public void Logoff()

  // Sending
  public void AddRecip( string name, string address, bool cc )
  public void Attach( string filepath )
  public bool Send( string subject, string text )

  // Finding
  public bool Next( ref MailEnvelop env )

  // Reading
  public string Read( string id, out MailAttach[] aat )
  public bool Delete( string id )
  public bool SaveAttachm( string id, string filename, string savepath )

  // Addressing
  public bool SingleAddress( string label, out string name, out string addr )

A small (e.g. console) client could do just this few steps:

Mapi ma = new Mapi();
ma.Logon( IntPtr.Zero );
ma.AddRecip( "", null, false );
ma.Send( "Subject", "Mail text here" );

Sample App

The source for a sample GUI (Windows Form) client and a console client are included in the download.


All code was tested only on Windows XP with MS Outlook XP in the internet-mode. On this system, some security warnings show-up if accessing MAPI. Any feedback for other environments (especially Exchange) are very welcome!


This article, along with any associated source code and files, is licensed under A Public Domain dedication


About the Author

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Comments and Discussions

GeneralFailure with App.config !!??!! Pin
ptorrsmith21-Nov-04 16:32
memberptorrsmith21-Nov-04 16:32 
Generalwon't work with XP + Outlook 2002/2003 Pin
topikpl16-Sep-04 22:17
membertopikpl16-Sep-04 22:17 
GeneralRe: won't work with XP + Outlook 2002/2003 Pin
Craigus_H10-Jan-05 8:15
memberCraigus_H10-Jan-05 8:15 
QuestionHow to make a script read new mails automatically ? Pin
faizq1-Sep-04 20:38
memberfaizq1-Sep-04 20:38 
QuestionWhat condition for MAPI? Pin
jewlin3-Feb-04 17:31
memberjewlin3-Feb-04 17:31 
GeneralUse in commercial application. Pin
abrian15-Jan-04 0:28
memberabrian15-Jan-04 0:28 
QuestionPassword ignored? Pin
banduraj8-Jan-04 7:45
memberbanduraj8-Jan-04 7:45 
AnswerRe: Password ignored? Pin
Jan Pichler22-May-04 13:22
sussJan Pichler22-May-04 13:22 
GeneralAdd repipientS Pin
Harald Geißelhart4-Jan-04 8:32
memberHarald Geißelhart4-Jan-04 8:32 
GeneralRe: Add repipientS Pin
NETMaster4-Jan-04 15:02
memberNETMaster4-Jan-04 15:02 
QuestionNice Article - Bulk Mail ? Pin
Braulio Dez23-Sep-03 1:59
memberBraulio Dez23-Sep-03 1:59 
GeneralAOL v8 Problem Pin
mike1orb18-Sep-03 17:20
membermike1orb18-Sep-03 17:20 
GeneralExtended MAPI to modify emails being sent Pin
Gorgrael29-May-03 19:46
memberGorgrael29-May-03 19:46 
GeneralRe: Extended MAPI to modify emails being sent Pin
NETMaster30-May-03 1:19
memberNETMaster30-May-03 1:19 
GeneralRead *.eml files Pin
AlexCode22-May-03 13:17
professionalAlexCode22-May-03 13:17 
GeneralRe: DllImport Pin
NETMaster23-Jan-03 15:25
memberNETMaster23-Jan-03 15:25 
GeneralRe: DllImport Pin
NETMaster26-Jan-03 13:21
memberNETMaster26-Jan-03 13:21 
GeneralMAPI Service Pin
fadi17-Dec-02 6:29
memberfadi17-Dec-02 6:29 
GeneralRe: MAPI Service Pin
NETMaster17-Dec-02 7:15
memberNETMaster17-Dec-02 7:15 
GeneralRe: MAPI Service Pin
ChainsawDon27-Feb-05 3:03
memberChainsawDon27-Feb-05 3:03 
GeneralVery Cool Pin
Anonymous11-Nov-02 15:33
memberAnonymous11-Nov-02 15:33 
Questionhow about other folders? Pin
Anonymous19-Oct-02 11:02
memberAnonymous19-Oct-02 11:02 
AnswerRe: how about other folders? Pin
NETMaster20-Oct-02 23:50
memberNETMaster20-Oct-02 23:50 
GeneralExchange Pin
Anonymous26-Sep-02 15:03
memberAnonymous26-Sep-02 15:03 
GeneralGreat sample Pin
Anonymous2-Sep-02 2:24
memberAnonymous2-Sep-02 2:24 

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