I deleted a site because I moved it to a different server. Now, whenever I try to send email to someone on that site, it gets returned from the server where it used to exist. I've changed the dns, deleted the site and emptied the trash. Any ideas?
Did you change the DNS records, so that the A_Record for the domain and the MX record point to the new server?
I deleted the primary dns record completely and changed the nameservers on the domain to point to a different dns server.
Does Code: dig mx yourdomain.com show the correct data? Also, it can take up to 72 hours until DNS changes propagate.