Topic: Log filling up with authentication failure?

[guest]

Hi,
My logs have thousands of entries as below, yet the user is loggend on already?

Mar  5 04:47:39 merlin PAM_pwdb[30990]: authentication failure; (uid=0) -> blake for imap service
Mar  5 04:47:40 merlin imapd[30990]: Login failure user=blake host=pc-00111 [10.58.48.111]
Mar  5 04:47:43 merlin imapd[30990]: Command stream end of file, while reading line user=blake host=pc-00111 [10.58.48.111]

I do not know what to do, or where to look.