Chris,
I'll respond to your last comment first. Technically speaking, when you add the sponsor's name/email they still aren't really the sender. The sender is ONA Surveys. However, when people get the email it will appear as if it come from the sender, but if you looked at the message details you can see that the email came from ONA Surveys. Then reply, then the email will now go to the sponsor's email address.
I can understand why you think it be more meaningful for it to say 'sender', but I guess we're just (trying) to make it clear that the email is not technically sent from the sender's email account.
Let me just check on the real question you have re out-of-office and bounces. I'll have an update on Monday (at the latest).
Cheers,
Cai