Changing From address on multiple email assets at once instead of one-by-one by hand.
Solution
You can use program/folder tokens as the from address, and then change the token. Once the token changes it will update the assets using the token. For any pre-existing emails, updates in bulk could be made through a API call to the Marketo API endpoint - http://developers.marketo.com/rest-api/assets/emails/#create_and_update.