Is there a way to update who an invoice comes from? We have a basic preparer/approver workflow where the invoice is approved and assuming the to be emailed box is ticked under communication-messages it gets sent from the approver. We'd like it to be sent from a different email address

Could just update their 'From' email address

@jglovsky Check out Bundle 19285. It's free. It automatically suppresses the native email and then emails to a number of other emails in custom fields that you've specified. It's not exactly what you're looking for, but you could use the same logic/functionality to update the from email address on the send email action (either within this workflow, or just use it as a reference to update your own workflow)