Under Messages, you can select any of the following message types you want Spy to monitor:
| Message | Description |
| Mouse | Mouse messages, such as WM_MOUSEMOVE and WM_SETCURSOR |
| Input | Input messages, such as WM_CHAR and WM_COMMAND |
| System | Systemwide messages, such as WM_ENDSESSION and WM_TIMECHANGE |
| Window | Window manager messages, such as WM_SIZE and WM_SHOWWINDOW |
| Init | Initialization messages, such as WM_INITMENU and WM_INITDIALOG |
| Clipboard | Clipboard messages, such as WM_RENDERFORMAT |
| Other | Messages other than the types explicitly listed |
| DDE | Dynamic data exchange (DDE) messages, such as WM_DDE_REQUEST |
| Non Client | Windows nonclient messages, such as WM_NCDESTROY and WM_NCHITTEST |
By default, Spy monitors all messages.