Again, read the man page for syslog.conf. Check your /etc/syslog.conf. It will show where the error messages are going. The /etc/syslog.conf IS your configuration file.
FreeBSD.org - syslog.conf man page
See the
Examples for setting up the configuration file to allow changing where and what gets logged. Make sure you are setting your logging low enough to catch messages (start with the lowest level and if you are getting more than what you wanted, cut it back).
To log to another server:
# emergency messages- log them on another machine.
*.emerg @arpa.berkeley.edu
On that other system you would need your syslog.conf to put those messages into a file:
# Emergency messages to /var/log/spoolerr
*.emerg /var/log/spoolerr
Note that this will send the messages from both servers to this file. You can't get around this via the syslog.conf.
Check that syslogd is running on both servers - once you change syslog.conf, you should be able to send a HUP signal to both syslogd processes and start getting messages from both servers into the spoolerr file.
As far as the -a option, insure the -s option isn't being used on either server (disallows logging from/to servers).
Once you insure you know where your messages are going (/etc/syslog.conf), and that your syslog daemons are allowing logging from/to remote servers (ps -ef|grep syslogd), then you can look to the -a option.