Hi @David Frankel
Unfortunately, this is not possible. But I have a suggestion if it's okay which I've seen other users use in the past.
You can create a "fake" contact under your org which you give the same name as the org itself but it's a person. This person just contains the email address. Now you can still bulk select those orgs in the person list and send out the email. In case you do use merge fields in templates you would need to copy over more fields as well. Not ideal but it does the trick.