//This code has been sourced from:
//https://www.add-in-express.com/creating-addins-blog/2009/05/08/outlook-exchange-email-address-smtp/
//https://www.add-in-express.com/files/howtos/blog/adx-ol-smtp-address-cs.zip
public static string ADX_GetSMTPAddress(string exchangeAddress)
{
string smtpAddress = string.Empty;
IAddrBook addrBook = ADX_GetAddrBook();
if (addrBook != null)
{
try {
IntPtr szPtr = IntPtr.Zero;
IntPtr propValuePtr = Marshal.AllocHGlobal(16);
IntPtr adrListPtr = Marshal.AllocHGlobal(16);
Marshal.WriteInt32(propValuePtr, (int)MAPI.PR_DISPLAY_NAME);
Marshal.WriteInt32(new IntPtr(propValuePtr.ToInt32() + 4), 0);
szPtr = Marshal.StringToHGlobalAnsi(exchangeAddress);
Marshal.WriteInt64(new IntPtr(propValuePtr.ToInt32() + 8), szPtr.ToInt32());
Marshal.WriteInt32(adrListPtr, 1);
Marshal.WriteInt32(new IntPtr(adrListPtr.ToInt32() + 4), 0);
Marshal.WriteInt32(new IntPtr(adrListPtr.ToInt32() + 8), 1);
Marshal.WriteInt32(new IntPtr(adrListPtr.ToInt32() + 12), propValuePtr.ToInt32());
try {
if (addrBook.ResolveName(0, MAPI.MAPI_DIALOG, null, adrListPtr) == MAPI.S_OK)
{
SPropValue spValue = new SPropValue();
int pcount = Marshal.ReadInt32(new IntPtr(adrListPtr.ToInt32() + 8));
IntPtr props = new IntPtr(Marshal.ReadInt32(new IntPtr(adrListPtr.ToInt32() + 12)));
for (int i = 0; i < pcount; i++)
{
spValue = (SPropValue)Marshal.PtrToStructure(
new IntPtr(props.ToInt32() + (16 * i)), typeof(SPropValue));
if (spValue.ulPropTag == MAPI.PR_ENTRYID)
{
IntPtr addrEntryPtr = IntPtr.Zero;
IntPtr propAddressPtr = IntPtr.Zero;
uint objType = 0;
uint cb = (uint)(spValue.Value & 0xFFFFFFFF);
IntPtr entryID = new IntPtr((int)(spValue.Value >> 32));
if (addrBook.OpenEntry(cb, entryID, IntPtr.Zero, 0, out objType, out addrEntryPtr) == MAPI.S_OK)
{
try {
if (MAPI.HrGetOneProp(addrEntryPtr, MAPI.PR_EMS_AB_PROXY_ADDRESSES, out propAddressPtr) == MAPI.S_OK)
{
IntPtr emails = IntPtr.Zero;
SPropValue addrValue = (SPropValue)Marshal.PtrToStructure(propAddressPtr, typeof(SPropValue));
int acount = (int)(addrValue.Value & 0xFFFFFFFF);
IntPtr pemails = new IntPtr((int)(addrValue.Value >> 32));
for (int j = 0; j < acount; j++)
{
emails = new IntPtr(Marshal.ReadInt32(new IntPtr(pemails.ToInt32() + (4 * j))));
smtpAddress = Marshal.PtrToStringAnsi(emails);
if (smtpAddress.IndexOf("SMTP:") == 0)
{
smtpAddress = smtpAddress.Substring(5, smtpAddress.Length - 5);
break;
}
}
}
}
finally {
if (propAddressPtr != IntPtr.Zero)
{
Marshal.Release(propAddressPtr);
}
if (addrEntryPtr != IntPtr.Zero)
{
Marshal.Release(addrEntryPtr);
}
}
}
}
}
}
}
finally {
Marshal.FreeHGlobal(szPtr);
Marshal.FreeHGlobal(propValuePtr);
Marshal.FreeHGlobal(adrListPtr);
}
}
finally {
Marshal.ReleaseComObject(addrBook);
}
}
return(smtpAddress);
}
