I used the following helper class.
class MAPI
{
public bool AddRecipientTo(string email)
{
return AddRecipient(email, HowTo.MAPI_TO);
}
public bool AddRecipientCC(string email)
{
return AddRecipient(email, HowTo.MAPI_TO);
}
public bool AddRecipientBCC(string email)
{
return AddRecipient(email, HowTo.MAPI_TO);
}
public void AddAttachment(string strAttachmentFileName)
{
m_attachments.Add(strAttachmentFileName);
}
public int SendMailPopup(string strSubject, string strBody)
{
return SendMail(strSubject, strBody, MAPI_LOGON_UI | MAPI_DIALOG);
}
public int SendMailDirect(string strSubject, string strBody)
{
return SendMail(strSubject, strBody, MAPI_LOGON_UI);
}
[DllImport("MAPI32.DLL")]
static extern int MAPISendMail(IntPtr sess, IntPtr hwnd,
MapiMessage message, int flg, int rsv);
int SendMail(string strSubject, string strBody, int how)
{
MapiMessage msg = new MapiMessage();
msg.subject = strSubject;
msg.noteText = strBody;
msg.recips = GetRecipients(out msg.recipCount);
msg.files = GetAttachments(out msg.fileCount);
m_lastError = MAPISendMail(new IntPtr(0), new IntPtr(0), msg, how,
0);
if (m_lastError > 1)
MessageBox.Show("MAPISendMail failed! " + GetLastError(),
"MAPISendMail");
Cleanup(ref msg);
return m_lastError;
}
bool AddRecipient(string email, HowTo howTo)
{
MapiRecipDesc recipient = new MapiRecipDesc();
recipient.recipClass = (int)howTo;
recipient.name = email;
m_recipients.Add(recipient);
return true;
}
IntPtr GetRecipients(out int recipCount)
{
recipCount = 0;
if (m_recipients.Count == 0)
return IntPtr.Zero;
int size = Marshal.SizeOf(typeof(MapiRecipDesc));
IntPtr intPtr = Marshal.AllocHGlobal(m_recipients.Count * size);
int ptr = (int)intPtr;
foreach (MapiRecipDesc mapiDesc in m_recipients)
{
Marshal.StructureToPtr(mapiDesc, (IntPtr)ptr, false);
ptr += size;
}
recipCount = m_recipients.Count;
return intPtr;
}
IntPtr GetAttachments(out int fileCount)
{
fileCount = 0;
if (m_attachments == null)
return IntPtr.Zero;
if ((m_attachments.Count <= 0) || (m_attachments.Count >
maxAttachments))
return IntPtr.Zero;
int size = Marshal.SizeOf(typeof(MapiFileDesc));
IntPtr intPtr = Marshal.AllocHGlobal(m_attachments.Count * size);
MapiFileDesc mapiFileDesc = new MapiFileDesc();
mapiFileDesc.position = -1;
int ptr = (int)intPtr;
foreach (string strAttachment in m_attachments)
{
mapiFileDesc.name = Path.GetFileName(strAttachment);
mapiFileDesc.path = strAttachment;
Marshal.StructureToPtr(mapiFileDesc, (IntPtr)ptr, false);
ptr += size;
}
fileCount = m_attachments.Count;
return intPtr;
}
void Cleanup(ref MapiMessage msg)
{
int size = Marshal.SizeOf(typeof(MapiRecipDesc));
int ptr = 0;
if (msg.recips != IntPtr.Zero)
{
ptr = (int)msg.recips;
for (int i = 0; i < msg.recipCount; i++)
{
Marshal.DestroyStructure((IntPtr)ptr,
typeof(MapiRecipDesc));
ptr += size;
}
Marshal.FreeHGlobal(msg.recips);
}
if (msg.files != IntPtr.Zero)
{
size = Marshal.SizeOf(typeof(MapiFileDesc));
ptr = (int)msg.files;
for (int i = 0; i < msg.fileCount; i++)
{
Marshal.DestroyStructure((IntPtr)ptr,
typeof(MapiFileDesc));
ptr += size;
}
Marshal.FreeHGlobal(msg.files);
}
m_recipients.Clear();
m_attachments.Clear();
m_lastError = 0;
}
public string GetLastError()
{
if (m_lastError <= 26)
return errors[m_lastError];
return "MAPI error [" + m_lastError.ToString() + "]";
}
readonly string[] errors = new string[] {
"OK [0]", "User abort [1]", "General MAPI failure [2]",
"MAPI login failure [3]", "Disk full [4]",
"Insufficient memory [5]", "Access denied [6]",
"-unknown- [7]", "Too many sessions [8]",
"Too many files were specified [9]",
"Too many recipients were specified [10]",
"A specified attachment was not found [11]",
"Attachment open failure [12]",
"Attachment write failure [13]", "Unknown recipient [14]",
"Bad recipient type [15]", "No messages [16]",
"Invalid message [17]", "Text too large [18]",
"Invalid session [19]", "Type not supported [20]",
"A recipient was specified ambiguously [21]",
"Message in use [22]", "Network failure [23]",
"Invalid edit fields [24]", "Invalid recipients [25]",
"Not supported [26]"
};
List<MapiRecipDesc> m_recipients = new
List<MapiRecipDesc>();
List<string> m_attachments = new List<string>();
int m_lastError = 0;
const int MAPI_LOGON_UI = 0x00000001;
const int MAPI_DIALOG = 0x00000008;
const int maxAttachments = 20;
enum HowTo { MAPI_ORIG = 0, MAPI_TO, MAPI_CC, MAPI_BCC };
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public class MapiMessage
{
public int reserved;
public string subject;
public string noteText;
public string messageType;
public string dateReceived;
public string conversationID;
public int flags;
public IntPtr originator;
public int recipCount;
public IntPtr recips;
public int fileCount;
public IntPtr files;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public class MapiFileDesc
{
public int reserved;
public int flags;
public int position;
public string path;
public string name;
public IntPtr type;
}
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public class MapiRecipDesc
{
public int reserved;
public int recipClass;
public string name;
public string address;
public int eIDSize;
public IntPtr entryID;
}
Use the MAPI class as below.
MAPI mapi = new MAPI();
mapi.AddAttachment("c:\\temp\\file1.txt");
mapi.AddAttachment("c:\\temp\\file2.txt");
mapi.AddRecipientTo("person1@somewhere.com");
mapi.AddRecipientTo("person2@somewhere.com");
mapi.SendMailPopup("testing", "body text");
// Or if you want try and do a direct send without displaying the
// mail dialog mapi.SendMailDirect("testing", "body text");
Reference: Code Project
