The IMAPISession::EnumAdrTypes method returns the address types that can be handled by all of the transport providers in the session.
HRESULT EnumAdrTypes(
ULONG ulFlags,
ULONG FAR * lpcAdrTypes,
LPTSTR FAR * FAR * lpppszAdrTypes
);
The IMAPISession::EnumAdrTypes method returns a list of the address types that can be handled by all of the active transport providers in the session. The address types for transport providers that are not currently loaded are not included in the list. Transport providers register to handle one or more address types when MAPI calls their IXPLogon::AddressTypes method.
Call MAPIFreeBuffer to release the string array pointed to by the lpppszAdrTypes parameter.