Dovecot Auth. Failure spams Message log

[d3m0nic]

Hello,

[CentOS 4.3 - LAMP - ISPc - Dovecot]

My message log is spammed by Dovecot. The same line keeps repeating on and on!

Aug 22 15:15:56 host1 dovecot(pam_unix)[24079]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:18:56 host1 dovecot(pam_unix)[24117]: check pass; user unknown
Aug 22 15:18:56 host1 dovecot(pam_unix)[24117]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:21:56 host1 dovecot(pam_unix)[24155]: check pass; user unknown
Aug 22 15:21:56 host1 dovecot(pam_unix)[24155]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:24:56 host1 dovecot(pam_unix)[24193]: check pass; user unknown
Aug 22 15:24:56 host1 dovecot(pam_unix)[24193]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:27:56 host1 dovecot(pam_unix)[24232]: check pass; user unknown
Aug 22 15:27:56 host1 dovecot(pam_unix)[24232]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:30:56 host1 dovecot(pam_unix)[24269]: check pass; user unknown
Aug 22 15:30:56 host1 dovecot(pam_unix)[24269]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:33:56 host1 dovecot(pam_unix)[24307]: check pass; user unknown
Aug 22 15:33:56 host1 dovecot(pam_unix)[24307]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:36:56 host1 dovecot(pam_unix)[24345]: check pass; user unknown
Aug 22 15:36:56 host1 dovecot(pam_unix)[24345]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:39:56 host1 dovecot(pam_unix)[24383]: check pass; user unknown
Aug 22 15:39:56 host1 dovecot(pam_unix)[24383]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:42:56 host1 dovecot(pam_unix)[24422]: check pass; user unknown
Aug 22 15:42:56 host1 dovecot(pam_unix)[24422]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:45:56 host1 dovecot(pam_unix)[24460]: check pass; user unknown
Aug 22 15:45:56 host1 dovecot(pam_unix)[24460]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=
Aug 22 15:48:56 host1 dovecot(pam_unix)[24498]: check pass; user unknown
Aug 22 15:48:56 host1 dovecot(pam_unix)[24498]: authentication failure; logname= uid=0 euid=0 tty= ruser= rhost=

Any idea what this is and how i can resolve this... or is this normal?

TIA,