diff --git a/Makefile b/Makefile
index 75afc05b..b2b49ce9 100644
--- a/Makefile
+++ b/Makefile
@@ -332,6 +332,7 @@ init_reverse: init_redis init_postgres
 		-v "`pwd`/test/share/passwd":/tmp/passwd \
 		-v "`pwd`/test/share/ssl/rsa":/var/mail/ssl \
 		-v "`pwd`/test/share/sieve/custom.sieve":/var/mail/sieve/custom.sieve \
+		-v "`pwd`/test/share/postfix/rbl_override":/etc/postfix/rbl_override \
 		-v "`pwd`/test/share/letsencrypt":/etc/letsencrypt \
 		-t $(NAME)
 fixtures_reverse:
@@ -556,7 +557,8 @@ fixtures_default:
 	@timeout $(WAIT_TIMEOUT) sh -c 'until [ -z "$$(docker exec mailserver_default find /var/spool/postfix/incoming /var/spool/postfix/active /var/spool/postfix/maildrop -type f 2>/dev/null)" ]; do sleep 2; done' \
 		|| { echo "TIMEOUT: postfix queue did not drain"; docker exec mailserver_default postqueue -p; exit 1; }
 run_default:
-	./test/bats/bin/bats test/default.bats
+	# Some tests start their own container, from this image
+	MAILSERVER_IMAGE=$(NAME) ./test/bats/bin/bats test/default.bats
 stop_default:
 	-docker rm -fv \
 		mailserver_default || true
diff --git a/rootfs/usr/local/bin/setup.sh b/rootfs/usr/local/bin/setup.sh
index f7977685..589bf409 100644
--- a/rootfs/usr/local/bin/setup.sh
+++ b/rootfs/usr/local/bin/setup.sh
@@ -313,21 +313,25 @@ fi
 #
 # Initialize rbl_override configuration
 #
-if [ -d "/etc/postifx/rbl_override" ]; then
-  echo "[ERROR] The `/etc/postfix/rbl_override` is a folder instead of a file.  Please fix it."
-  exit 1;
-fi
-
-if [ ! -f "/etc/postfix/rbl_override" ]; then
+if [ -d "/etc/postfix/rbl_override" ]; then
+  echo "[ERROR] /etc/postfix/rbl_override is a folder instead of a file. Please fix it."
+  touch /etc/setup-error
+elif [ ! -f "/etc/postfix/rbl_override" ]; then
   touch /etc/postfix/rbl_override
   echo "[INFO] Created default (empty) rbl_override file"
 else
   echo "[INFO] /etc/postfix/rbl_override file found"
 fi
 
+# -o keeps root privileges. Without it postmap runs as the owner of a non-root
+# file, typically a bind mount, and cannot write the .db into /etc/postfix.
 if [ -f "/etc/postfix/rbl_override" ]; then
-  postmap /etc/postfix/rbl_override
-  echo "[INFO] RBL Override initialized"
+  if postmap -o /etc/postfix/rbl_override; then
+    echo "[INFO] RBL Override initialized"
+  else
+    echo "[ERROR] Could not build the rbl_override map, see the postmap error above."
+    touch /etc/setup-error
+  fi
 fi
 
 # DOVECOT TUNING
diff --git a/test/default.bats b/test/default.bats
index 5056f974..c796ed04 100644
--- a/test/default.bats
+++ b/test/default.bats
@@ -45,6 +45,50 @@ load 'test_helper/bats-assert/load'
   assert_failure
 }
 
+# A bind mount whose host file is missing makes Docker create a directory in its
+# place, and Postfix cannot use that as a map. The timeout turns a container that
+# starts anyway into a failed test rather than a hung suite.
+@test "checking system: startup stops when rbl_override is a directory" {
+  run timeout 180 docker run --rm \
+    --name mailserver_default_rbl_dir \
+    --link mariadb:mariadb \
+    --link redis:redis \
+    -e DBPASS=testpasswd \
+    -e RSPAMD_PASSWORD=testpasswd \
+    -e VMAILUID=`id -u` \
+    -e VMAILGID=`id -g` \
+    -e DISABLE_CLAMAV=true \
+    -e TESTING=true \
+    --tmpfs /etc/postfix/rbl_override \
+    -h mail.domain.tld \
+    "${MAILSERVER_IMAGE:-mailserver2/mailserver:testing}"
+  docker rm -f mailserver_default_rbl_dir > /dev/null 2>&1 || true
+  assert_failure 1
+  assert_output --partial "[ERROR] /etc/postfix/rbl_override is a folder instead of a file"
+}
+
+# Without the map, Postfix answers RCPT from clients outside mynetworks with
+# 451 4.3.5, so a failed postmap must stop startup. A directory mounted where
+# the .db goes makes postmap fail.
+@test "checking system: startup stops when the rbl_override map cannot be built" {
+  run timeout 180 docker run --rm \
+    --name mailserver_default_rbl_db \
+    --link mariadb:mariadb \
+    --link redis:redis \
+    -e DBPASS=testpasswd \
+    -e RSPAMD_PASSWORD=testpasswd \
+    -e VMAILUID=`id -u` \
+    -e VMAILGID=`id -g` \
+    -e DISABLE_CLAMAV=true \
+    -e TESTING=true \
+    --tmpfs /etc/postfix/rbl_override.db \
+    -h mail.domain.tld \
+    "${MAILSERVER_IMAGE:-mailserver2/mailserver:testing}"
+  docker rm -f mailserver_default_rbl_db > /dev/null 2>&1 || true
+  assert_failure 1
+  assert_output --partial "[ERROR] Could not build the rbl_override map"
+}
+
 #
 # processes (default configuration)
 #
@@ -522,6 +566,11 @@ load 'test_helper/bats-assert/load'
   assert_output "/tmp"
 }
 
+@test "checking postfix: rbl_override map is built when none is provided" {
+  run docker exec mailserver_default test -f /etc/postfix/rbl_override.db
+  assert_success
+}
+
 @test "checking postfix: headers cleanup" {
   run docker exec mailserver_default /bin/sh -c "grep -i 'replace: header Received' /var/log/mail.log | wc -l"
   assert_success
diff --git a/test/reverse.bats b/test/reverse.bats
index 94c43ada..cf27b601 100644
--- a/test/reverse.bats
+++ b/test/reverse.bats
@@ -424,6 +424,20 @@ load 'test_helper/bats-assert/load'
   assert_success
 }
 
+# By default postmap drops root privileges and runs as the source file's owner,
+# who cannot write the .db into /etc/postfix. The fixture is bind-mounted from
+# the checkout, so it belongs to the user running the suite; the first check
+# makes sure that is not root, or this test could not fail.
+@test "checking postfix: rbl_override map is built from a file not owned by root" {
+  run docker exec mailserver_reverse stat -c %u /etc/postfix/rbl_override
+  assert_success
+  refute_output "0"
+
+  run docker exec mailserver_reverse postmap -q 192.0.2.1 hash:/etc/postfix/rbl_override
+  assert_success
+  assert_output "OK"
+}
+
 #
 # dovecot
 #
diff --git a/test/share/postfix/rbl_override b/test/share/postfix/rbl_override
new file mode 100644
index 00000000..b8b876e2
--- /dev/null
+++ b/test/share/postfix/rbl_override
@@ -0,0 +1 @@
+192.0.2.1 OK