Where in debian can I disable a service from starting? I had installed courier-imap so I can use Maildir, but that did not work out too good, so I uninstalled it and installed dovecot so I can just use Mbox which is 100 times simpler, but it apears some courier related services stayed stuck, and start, and they take over the socket so dovecot can't start properly, but since half the courier stuff is gone, it can't find any files and basically does not do anything except for listening on port 143 and dropping any incoming connections. Instead of adding the required killall lines in my startup file, how do I stop it from loading altogether?