"No one at this address"-Delivery Failure Status

I have had this email through Homestead for years: Croark. Recently I created another account  under: Carolann and had two emails accounts at once. To limit some of the hassle i forwarded all emails from Carolann to Croark. No problems when people sent emails. Then, I deleted the Croark email and unchecked the forwarding option in the Carolann account. However, once I deleted the Croark account people have been receiving "delivery failure" emails-even though I am getting the emails in the correct account. It tells them "no one at this address". Not sure how that is possible since the account is verified, and I have been receiving all emails sent to me. Where do I go from here to ensure the person sending the email doesn't keep getting a delivery failure notification?