fixed logging in spampd and postfix

spampd/Dockerfile

@@ -15,8 +15,11 @@ sed -e's/LISTENHOST=127.0.0.1/LISTENHOST=0.0.0.0/' \
   -e's/CHILDREN=3/CHILDREN=2/' \
   -e's|ADDOPTS=""|ADDOPTS="--homedir=/var/lib/spamassassin/.spamassassin"|' \
   -i /etc/default/spampd
+# https://github.com/moby/moby/issues/31243#issuecomment-406879017
 sed -i '/imklog/s/^/#/' /etc/rsyslog.conf
-ln -sf /dev/stdout /var/log/syslog
+sed -e's|-/var/log/syslog|/dev/stdout|' \
+  -i /etc/rsyslog.d/50-default.conf
+usermod -G tty syslog
 usermod debian-spamd -l spamd -s /bin/bash
 groupmod debian-spamd -n spamd
 mkdir /var/run/spampd