OK, from eMail Verifier's Connection log when I retried two addresses, neither my own:
[01] 3/4 11:17:24 MX <
[email protected]> -> [mx-caprica.easydns.com,mx-caprica.easydns.com]
[01] 3/4 11:17:24 > CONNECT TO: [mx-caprica.easydns.com]
[01] 3/4 11:17:25 Error #64
[01] 3/4 11:17:25 Trying...