Various un-breaking

compose.mailrelay.yml

@@ -7,8 +7,6 @@ services:
     environment:
       - SMTP_HOST=${SMTP_HOST}
       - MAIL_FROM=${MAIL_FROM}
-    networks:
-      - mail
     configs:
       - source: mstmp_conf
         target: /etc/msmtprc
@@ -16,10 +14,6 @@ services:
         target: /docker-entrypoint.mailrelay.sh
         mode: 0555
 
-networks:
-  mail:
-    external: true
-
 configs:
   mstmp_conf:
     name: ${STACK_NAME}_mstmp_conf_${MSMTP_CONF_VERSION}