Mail forwarded between 2 accounts

I have 2 accounts, *** Email address is removed for privacy *** and *** Email address is removed for privacy ***. I have set it up so that mail sent to *** Email address is removed for privacy *** is automatically forwarded to *** Email address is removed for privacy ***. The *** Email address is removed for privacy *** account is being discontinued. My question is, in the future, if Sam sends an email to *** Email address is removed for privacy ***, even though it will have been discontinued, will that email be returned to Sam saying that the account does not exist OR will the email be forwarded to my *** Email address is removed for privacy *** account? I hope someone understands what it is that I'm asking. All responses are appreciated:)