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Posted 30 Mar 2002


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30 Mar 2002Public Domain
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

Questioncan simple MAPI run without STAThread? Pin
Member 1479008120-Apr-20 0:07
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QuestionCan i send email automatically Pin
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QuestionCan Use MAPI in ASP MVC? Pin
j.ghadiri19-Dec-18 3:32
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BugCannot save bitmap after e-mail Pin
Siddiqui's6-May-15 4:08
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QuestionFixed arithmetic overflow with pointer Pin
AJC Software23-Jan-15 0:07
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GeneralWriting a PST file with non email items without outlook installed Pin
uddipto8-Aug-12 0:01
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GeneralMy vote of 5 Pin
Manoj Kumar Choubey26-Feb-12 18:23
professionalManoj Kumar Choubey26-Feb-12 18:23 
QuestionSend Items Pin
loende12-Oct-11 8:26
Memberloende12-Oct-11 8:26 
Question.NET and Microsoft's MAPI DLL are not compatible. Pin
BMaguire27-Sep-11 15:08
MemberBMaguire27-Sep-11 15:08 
SuggestionMAPILogon failed with 80004005, BUT: Pin
Pascal Damman19-Jul-11 2:48
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QuestionConsole Application vs. GUI Application Pin
Bart Huls21-Apr-11 4:37
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GeneralMy vote of 5 Pin
waritsar23-Aug-10 0:25
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GeneralProblems with Login on Vista with Office 2007 Pin
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GeneralThanks Pin
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QuestionIs it possible to decrease the time for enabling the allow button on the security warning programmatically Pin
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AnswerRe: Is it possible to decrease the time for enabling the allow button on the security warning programmatically Pin
british27-Nov-08 9:28
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GeneralAwesome sample Pin
jchalfant21-May-08 6:09
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Questionhow to read mail from directly exchange server Pin
usha gupta9-Mar-08 20:39
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QuestionIs it possible? [modified] Pin
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Questionread mail which is in folder that is out from indox Pin
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QuestionHow to send HTML page as body Pin
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GeneralProblems setting the messageTypeProperty Pin
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GeneralRe: Problems setting the messageTypeProperty Pin
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GeneralRe: Problems setting the messageTypeProperty Pin
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QuestionGet only the last received mail from thunderbird Pin
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