put all DKIM on the primary hostname since that's the only one guaranteed to be actually hosted (DNS) here; give new users a Spam folder too

scripts/dns.sh

@@ -19,8 +19,12 @@ sudo mkdir -p /var/run/nsd3
 mkdir -p "$STORAGE_ROOT/dns";
 
 # Store our desired IP address (to put in the zone files) for later.
+# Also store our primary hostname, which we'll use for all DKIM signatures
+# in case the user is only delegating MX and we aren't setting DKIM on
+# the main DNS.
 
 echo $PUBLIC_IP > $STORAGE_ROOT/dns/our_ip
+echo $PUBLIC_HOSTNAME > $STORAGE_ROOT/dns/primary_hostname
 
 # Create the default zone if it doesn't exist.
 

scripts/dns_update.sh

@@ -2,6 +2,15 @@
 
 source /etc/mailinabox.conf
 PUBLIC_IP=`cat $STORAGE_ROOT/dns/our_ip`
+PRIMARY_HOSTNAME=`cat $STORAGE_ROOT/dns/primary_hostname`
+
+# Ensure a zone file exists for every domain name of a mail user.
+for mail_user in `tools/mail.py user`; do
+	domain=`echo $mail_user | sed s/.*@//`
+	if [ ! -f $STORAGE_ROOT/dns/$domain.txt ]; then
+		echo "" > $STORAGE_ROOT/dns/$domain.txt;
+	fi
+done
 
 # Create the top of nsd.conf.
 
@@ -80,7 +89,10 @@ EOF
 
 	# OpenDKIM
 	
-	echo "$zone $zone:mail:$STORAGE_ROOT/mail/dkim/mail.private" >> /etc/opendkim/KeyTable
+	# For every domain, we sign against the key listed in PRIMARY_HOSTNAME's DNS,
+	# in case the user is just delegating MX and hasn't set the DKIM info on the
+	# main DNS record.
+	echo "$zone $PRIMARY_HOSTNAME:mail:$STORAGE_ROOT/mail/dkim/mail.private" >> /etc/opendkim/KeyTable
 	echo "*@$zone $zone" >> /etc/opendkim/SigningTable
 
 done

scripts/start.sh

@@ -38,6 +38,7 @@ fi
 
 cat > /etc/mailinabox.conf << EOF;
 STORAGE_ROOT=$STORAGE_ROOT
+PUBLIC_HOSTNAME=$PUBLIC_HOSTNAME
 EOF
 
 . scripts/system.sh

tools/mail.py

@@ -51,6 +51,7 @@ elif sys.argv[1] == "user" and sys.argv[2] in ("add", "password"):
 		# Create the user's INBOX and subscribe it.
 		conn.commit() # write it before next step
 		subprocess.check_call(["doveadm", "mailbox", "create", "-u", email, "-s", "INBOX"])
+		subprocess.check_call(["doveadm", "mailbox", "create", "-u", email, "-s", "Spam"])
 	elif sys.argv[2] == "password":
 		c.execute("UPDATE users SET password=? WHERE email=?", (pw, email))
 		if c.rowcount != 1: