Getting error while starting, stopping or reloading SpamAssassin

[webmaster <we...@my-it-brain.de>]

Hi folks,

I'm very new to SpamAssassin and have some issues getting log messages I
can't get rid of.

I'm running a server with ubuntu 14.04.1 and spamassassin version
3.4.0-1ubuntu2. Spamassassin was installed from the ubuntu repositories.

1. When I stop spamassassin I get the following message:
sudo service spamassassin stop
Stopping SpamAssassin Mail Filter Daemon: No /usr/bin/perl found
running; none killed.
spamd.

2. When starting the service I get:
:~$ sudo service spamassassin start
Starting SpamAssassin Mail Filter Daemon: child process [1757] exited or
timed out without signaling production of a PID file: exit 255 at
/usr/sbin/spamd line 2960.

What's wrong here?

3. I searched in my log files and found in /var/log/mail.err:
Dec 23 00:17:26 hostname spamd[1757]: Timeout::_run: check: no loaded
plugin implements 'check_main': cannot scan!
Dec 23 00:17:26 hostname spamd[1757]: Check the necessary '.pre' files
are in the config directory.
Dec 23 00:17:26 hostname spamd[1755]: child process [1757] exited or
timed out without signaling production of a PID file: exit 255 at
/usr/sbin/spamd line 2960.
Dec 23 00:18:08 hostname spamass-milter[1781]: spamass-milter 0.3.2 starting

Is here something wrong with the binary in /usr/sbin/spamd?

4. In /var/log/mail.log I found this:
spamd[1755]: logger: removing stderr method
spamd[1757]: Timeout::_run: check: no loaded plugin implements
'check_main': cannot scan!
spamd[1757]: Check the necessary '.pre' files are in the config directory.
spamd[1755]: child process [1757] exited or timed out without signaling
production of a PID file: exit 255 at /usr/sbin/spamd line 2960.

Could anyone help me, to get rid of this errors? I would appreciate if
someone could explain to me what went wrong in my setup.

Best Regards
John