Reset myhostname to avoid build server rDNS being used, add some note…

…s and info when fixing spool dir

Dockerfile

@@ -40,6 +40,7 @@ RUN set -x \
 
 # Configure Postfix / dkim
 RUN set -x \
+  && postconf -e myhostname="localhost" \
   && postconf -e smtpd_banner="\$myhostname ESMTP" \
   && postconf -Me submission/inet="submission inet n - y - - smtpd" \
   && postconf -Me 2525/inet="2525 inet n - y - - smtpd" \

s6/postfix/run

@@ -30,10 +30,12 @@ unset LANG
 cd /etc/postfix
 
 # Copy default spool from cache
+# Note: this test may get confused if a volume is mounted that already contains unrelated directories (eg lost+found)
 if [ ! "$(ls -A /var/spool/postfix)" ]; then
-   cp -a /var/spool/postfix.cache/* /var/spool/postfix/
+  echo "postfix >> Copying postfix spool directory from postfix.cache (from the image)"
+  cp -a /var/spool/postfix.cache/* /var/spool/postfix/
 else
-  # Fix spool directory permissions
+  echo "postfix >> Fixing/resetting spool directory permissions"
   chgrp -R postdrop /var/spool/postfix/public
   chgrp -R postdrop /var/spool/postfix/maildrop
   postfix set-permissions