Demystifying the Microsoft Outlook 16.0 Object Library: Safe Implementation and Alternatives

Instead:

Open the application where you are writing VBA (e.g., Excel or Outlook). Press to open the VBA Editor. Click Tools > References . Look for Microsoft Outlook 16.0 Object Library .

Open the host application (such as Excel or Access) where your macro is stored. Press to open the VBA Editor. In the top menu, click on Tools and select References .

Outlook.Application oApp = new Outlook.Application(); Outlook.MailItem mail = oApp.CreateItem(Outlook.OlItemType.olMailItem); mail.To = "someone@example.com"; mail.Subject = "Test"; mail.Body = "Hello from .NET"; mail.Send();

How to restore it (practical steps)

Microsoft never provides core Office DLLs as standalone downloads on public repositories (except via official channels like MSDN or Visual Studio installers).

Open your Office application and press ALT + F11 to open the VBA Editor. Click in the top menu, then select References .

If Outlook is installed but your macro does not recognize it, you simply need to turn the reference on: