The MAPI Store Accessor is a free .NET component from Add-in Express™ designed to provide developers with access to low‑level Extended MAPI features within Microsoft® Windows® Forms applications and .NET‑based COM add‑ins for Microsoft Outlook. It enables access to MAPI notifications, properties, and events not exposed through the Outlook Object Model. The component works with Microsoft Outlook versions 2000, 2002 (XP), 2003, 2007, and 32‑bit Outlook 2010. It can be used within Visual Studio .NET 2005, 2008, and 2010. Both Microsoft Outlook and Microsoft Exchange serve as sophisticated wrappers over the MAPI subsystem, but they do not expose all MAPI functionality. The MAPI Store Accessor fills gaps such as missing event details when users delete multiple items, modify explorer windows, or remove the last item in a folder. It connects either to the current Outlook profile or to a specified profile using credentials, and supports synchronous or asynchronous event handling.

Features

• Access to MAPI notifications: Subscribe to events including OnNewMail, OnObjectCopied, OnObjectCreated, OnObjectDeleted, OnObjectModified, OnObjectMoved, OnExtendedNotification, and OnSearchComplete.
• Extended event control: Capture events the Outlook Object Model does not provide, such as last‑item deletion or bulk operations.
• Flexible initialization options:
  • Initialize(false) – Connect to Outlook running in the current session.
  • Initialize(true) – Create a standalone MAPI session.
  • Initialize(profile, password) – Connect to a specific profile.
• Async event handling: Set polling intervals via the Interval property.
• Property access:
  • Retrieve MAPI properties via GetProperties or GetProperty.
  • Set properties via SetProperties or SetProperty.
  • Delete properties via DeleteProperties or DeleteProperty.
• Error handling: Access detailed diagnostics through the LastError property.
• Supported object types: Outlook item types, Folder, Store, AddressEntry, AddressList, Attachment, Recipient, ExchangeUser, ExchangeDistributionList.
• Type conversion: Returns .NET types based on MAPI property type (e.g., PT_UNICODE → string, PT_BINARY → byte[]).
• Deployment support: Requires Visual C++ Runtime Libraries (x86) SP1.
• Development compatibility:
  • Supported languages: C#, VB.NET, C++.
  • Supported .NET runtime: .NET 2.0.
  • Supported Visual Studio versions: 2005 and 2008 (Standard & Professional).
• Included resources: Class reference, C# and VB.NET demo projects.

Benefits

• Enhanced Outlook integration by exposing events and MAPI features not available through standard APIs.
• Improved performance using bulk property operations (GetProperties/SetProperties).
• More reliable add‑ins thanks to detailed error information and direct extended MAPI access.
• Flexibility to operate either as part of Outlook or as a standalone MAPI client.
• Greater control over Outlook data through direct property access and manipulation.
• Developer-friendly tooling with demo projects and documentation included in the installation package.