Outlook Window Hook

Keeps Outlook running in the background when the main window is closed, similar to Teams

Currently only works with the new Outlook client - if there's enough interest I'd be happy to implement support for older versions!

Download

You can find the installer or a standalone version on the Releases page here - please note for the standalone version OlkWindowHook.dll must be in the same directory as OlkWindowHook.exe

Features

Option to add to Startup (after running, right click the system tray icon and tick Autostart)
No need for admin privileges - installs to your AppData folder

How it works

Checks for new instances of olk.exe every 0.5 seconds
If a new instance is found, hooks in to the first window created
Intercepts the WM_CLOSE event and instead calls ShowWindow(pCwp->hwnd, SW_HIDE)

Building the installer

To build the OlkWindowHook.Installer project requires the Windows SDK MSI Tools. You will need to make sure that the OlkWindowHook.Installer project properties (namely the PostBuildEvent) point to your installation of MsiInfo.exe - this is required to set the flags on the installer to indicate admin rights aren't required

Licence

GPL-3.0