dovecot_login accepts blank password for exim smtp auth

Hi all, I recently discovered a configuration issue on my system where a system user account had a blank rather than invalid or disabled password in the passwd/shadow database.   The user could not be logged into through login/telnet/ssh because it was marked as a system account (uid < 100). 

[Dovecot] tiny doc bug report

First timer, I'm installing dovecot-2.0.15. I ran configure; make; sudo make install The INSTALL file then says: --- Rename configuration file: mv /usr/local/etc/dovecot-example.conf /usr/local/etc/dovecot.conf Read through, and make needed modifications. --- The example configuration file