[Dovecot] logging

[F. Even]

I'm curious about exactly what this means in my log:

Mar 13 10:56:20 cerebus dovecot: imap-login: Disconnected [130.94.242.20]
Mar 13 10:56:51 cerebus last message repeated 177 times
Mar 13 10:57:32 cerebus last message repeated 179 times

Now...does Dovecot ONLY log the names of users on successful attempts?  Is
this "Disconnected" log entry an indication someone ran a
username/password attack against the imap server and failed to
authenticate?  If so, is there any way to make this a little more verbose,
so I can perhaps see what names, etc. the annoying idiot is throwing
against my server....?

Thanks.