In general, ctiosy.ctio.noao.edu is the main email server used by staff and visitors at CTIO. (Some CTIO personnel such as AOSS have a seperate server).
In order to read email, a user within the CTIO network could log into ctiosy and use the ancient mail program to read and send mail, but this is not recommended and in future may not even be allowed. Much better is to set up an email client such as Thunderbird (or the Mozilla, Netscape variants), or Microsoft Outlook to access the server via IMAP. POP is deprecated and should not be used since IMAP is much more robust and secure, and runs faster to boot.
In some cases email can be sent directly to a particular user's account at CTIO, but this is somewhat unsafe since this means a hacker thus knows the name of an account on a CTIO machine and only needs to guess the password. It is recommended that email be sent to a users email alias.
To send electronic mail to someone at CTIO, one typically uses the following address formation syntax:
[first_initial][last_name]@ctio.noao.edu
Thus, to send email to Jim Hughes, try
jhughes@ctio.noao.edu
The formal NOAO alias email address for a VISITOR is given by:
[visitor_account]ctio@ctio.noao.edu
For example, for visitor 'v0':
v0ctio@ctio.noao.edu
Since CTIO and NOAO share a common list of aliases, in general addresses like 'jhughes@noao.edu' would work just as well as 'jhughes@ctio.noao.edu'.