sorry, for some reason your post went unnoticed. Yes, it's possible, in the Advanced panel just after the composer, you can type in a different sender address and a sender name for each newsletter.
Hi - I have a related question. Is there a way to have different sender email addresses when using the auto-responder to send out a timed series of emails? We have several different teams that want to be able to send out a series of welcome emails from their own team email.