diff --git a/postfixd.sh b/postfixd.sh
index 4fd0e2a..8f4c93c 100755
--- a/postfixd.sh
+++ b/postfixd.sh
@@ -2,6 +2,11 @@
 
 case $1 in
   start)
+    if test -z "${RSPAMD}" ; then
+      echo "Missing rspamd hostname" >&2
+      exit 1
+    fi
+
     # Reconfigure postfix according to environment
     postconf -e myhostname="${SUTTY}"
     postconf -e mydomain="${SUTTY}"