Simplify configuration

Postfix has an option to run in foreground. Use this feature to
reduce the complexity of supervisord.conf.

configs/supervisord.conf

@@ -16,11 +16,10 @@ stdout_logfile_maxbytes = 0
 stderr_logfile_maxbytes = 0
 
 [program:postfix]
-process_name    = master
+command         = /usr/sbin/postfix -c /etc/postfix start-fg
 autostart       = true
 autorestart     = false
 directory       = /etc/postfix
-command         = /usr/sbin/postfix -c /etc/postfix start
 startsecs       = 0
 
 [program:opendkim]

scripts/common-run.sh

@@ -171,7 +171,7 @@ postfix_setup_sender_domains() {
 		# Since we are behind closed doors, let's just permit all relays.
 		postconf -e "smtpd_relay_restrictions=permit"
 	elif [ -z "$ALLOW_EMPTY_SENDER_DOMAINS" ]; then
-		echo -e "ERROR: You need to specify ALLOWED_SENDER_DOMAINS otherwise Postfix will not run!"
+		error "You need to specify ALLOWED_SENDER_DOMAINS otherwise Postfix will not run!"
 		exit 1
 	fi
 }

scripts/run.sh

@@ -29,5 +29,5 @@ opendkim_custom_commands            # Apply custom OpenDKIM settings
 postfix_open_submission_port        # Enable the submission port
 execute_post_init_scripts           # Execute any scripts found in /docker-init.db/
 
-notice " Starting: ${emphasis}rsyslog${reset}, ${emphasis}postfix${reset}$DKIM_ENABLED"
+notice "Starting: ${emphasis}rsyslog${reset}, ${emphasis}postfix${reset}$DKIM_ENABLED"
 exec supervisord -c /etc/supervisord.conf