You can open an existing folder if you know either its entry identifier or the value of its Display-Name property. It is faster to use the entry identifier if it is known.
– Or –
The following sample code shows the call to open the root folder of an information store:
// Open the parent (or root) folder...
hr = lpMsgStore->OpenEntry(
0L, // use 0L for root folder
NULL, // use NULL for root folder
NULL, // use NULL for interface ID
MAPI_MODIFY | MAPI_DEFERRED_ERRORS, // use this flag if you plan to make changes
&ulObjType,
(LPUNKNOWN*)&lpParentFolder);