Published: July 16, 2012
Creates a new subfolder.
When CreateFolder returns, be aware that the entry identifier for the new folder might not be available. Some message store providers do not make entry identifiers available until after you have called the new folder's IMAPIProp::SaveChanges method to permanently save it. This is especially true if you have set the MAPI_DEFERRED_ERRORS flag.
Be aware that some message store providers always point the lppFolder parameter to the folder's standard interface, regardless of the value that you pass in for the lpInterface parameter. Because the interface pointer that is returned might not be of the type that you expect, call the new folder's IMAPIProp::GetProps method to retrieve the PR_OBJECT_TYPE (PidTagObjectType) property. If necessary, cast the pointer to a more appropriate type before you make other calls.
Most message store providers require the name of the new folder to be unique with respect to the names of its sibling folders. Be able to handle the MAPI_E_COLLISION error value, which is returned if this rule is not followed.
To determine the entry identifier of the newly created folder, call the new folder's IMAPIProp::GetProps method to retrieve its PR_ENTRYID (PidTagEntryId) property.