Is it possible to change the On-Send default message?

Question

Is it possible to change the On-Send default message using the Outlook Add-in API?

I have an add-in where I am stopping the email from being sent using:

currentEvent.completed({ allowEvent: false });

I tried doing this, but it didn't work. Does anyone know the "key" Outlook uses so I can replace that message?

Office.context.mailbox.item.notificationMessages.replaceAsync("onSendEvent", {
          type: Office.MailboxEnums.ItemNotificationMessageType.InformationalMessage,
          message: "Custom On-Send Message",
          persistent: false
        });