[in] The byte count in the entry identifier pointed to by the lpEntryID parameter.
[in] A pointer to the entry identifier of the object to open.
[in] A pointer to the interface identifier (IID) that represents the interface to be used to access the object. Passing NULL results in the object's standard interface being returned. For example, if the object to be opened is a message, the standard interface is IMessage; for folders, it is IMAPIFolder. The standard interfaces for address book objects are IDistList for a distribution list and IMailUser for a messaging user.
[in] A bitmask of flags that controls how the object is opened. The following flags can be set:
Requests that the object be opened with the maximum network permissions allowed for the caller. For example, if the caller has read/write permission, the object should be opened as read/write; if the caller has read-only permission, the object should be opened as read-only.
Allows OpenEntry to return successfully, possibly before the object is fully accessible to the caller. If the object is not accessible, making a subsequent object call can result in an error.
Requests read/write permission. By default, objects are opened as read-only, and callers should not work on the assumption that read/write permission has been granted.
[out] A pointer to the type of the opened object.
[out] A pointer to a pointer to the opened object.
The IMAPISupport::OpenEntry method is implemented for all service provider support objects. Service providers call IMAPISupport::OpenEntry to retrieve a pointer to an interface that can be used to access a particular object.
Call IMAPISupport::OpenEntry only when you do not know what kind of object you are opening. If you know you are opening a folder or a message, call IMsgStore::OpenEntry instead. If you know you are opening an address book container, a messaging user, or a distribution list, call IAddrBook::OpenEntry. These more specific methods are faster than IMAPISupport::OpenEntry.
IMAPISupport::OpenEntry opens all objects as read-only, unless you set the MAPI_MODIFY or MAPI_BEST_ACCESS flag in the ulFlags parameter and your permissions are sufficient. Setting one of these flags does not guarantee a particular type of access; the permissions that you are granted depend on your access level, the object, and the service provider that owns the object. To determine the access level of the opened object, retrieve its PR_ACCESS_LEVEL (PidTagAccessLevel) property.
Check the value returned in the lpulObjType parameter to determine that the object type returned is what you expected. If the object type is as expected, cast the pointer from the lppUnk parameter to a pointer of the appropriate type. For example, if you are opening a folder, cast lppUnk to a pointer of type LPMAPIFOLDER.