I suggest you try both sac.uky.edu and satchmo.cs.uky.edu to see the differences. VRFY raphael . The server will verify that the account raphael exists and give you the full user name. Some servers refuse to answer this question for security reasons. The server will break the connection.
Mail is insecure.
Intruders can snoop your mail while it is in transit. Software administrators can look at your mail while it is enqueued to be received. They will do so if there are problems with the mail program. File backups are likely to save your messages at the recipient's machine for very long periods of time. Therefore, never send private information through e-mail.