A partir da referência de comutador de linha de comando do Office :
/c messageclass
Creates a new item of the specified message class (Outlook forms or any other valid MAPI form).
Examples:
- /c ipm.activity creates a Journal entry
- /c ipm.appointment creates an appointment
- /c ipm.contact creates a contact
- /c ipm.note creates an e-mail message
- /c ipm.stickynote creates a note
- /c ipm.task creates a task
Então, isso deve fazer o truque
\Path\to\outlook.exe /c ipm.stickynote