[Wlug] Disable telnet and ssh, but ftp and email still enable!

Hi all, I have several user in my linux machine. And now, I've just finished configure my qmail server. qmail only works for the user who has the home directory. by this, I've got to create several users with their directory if I want to create an email address for them. It's not secure! How can I make disable ssh and telnet to my user ? By this my user still can access the email and ftp, but can not login via telnet and ssh service. what configuration that I need to do ? Thanks Man.