Check Postfix config before spawning Postfix procs

data/Dockerfiles/postfix/postfix.sh

@@ -6,6 +6,11 @@ sed -i "/^user/c\user = ${DBUSER}" /opt/postfix/conf/sql/*
 sed -i "/^password/c\password = ${DBPASS}" /opt/postfix/conf/sql/*
 sed -i "/^dbname/c\dbname = ${DBNAME}" /opt/postfix/conf/sql/*
 
-postfix -c /opt/postfix/conf start
-
-sleep infinity
+postconf -c /opt/postfix/conf
+if [[ $? != 0 ]]; then
+	echo "Postfix configuration error, refusing to start."
+	exit 1
+else
+	postfix -c /opt/postfix/conf start
+	sleep infinity
+fi