How do I notify a user I moved their post without using PM

I'm working on some API calls that, at some point, require me to notify the user of an action. I can't use PM and I don't know if they're subscribed to anything.

The UI move flow includes an option NOT to notify users, but the API call doesn't trigger any kind of notification(s).

How do I let the user know I moved their post (using the API)?