diff --git a/Dockerfile b/Dockerfile
index 884a715..fa49011 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -96,6 +96,7 @@ RUN echo "_dev_null: /dev/null" > /etc/aliases \
      scache/unix/chroot=n
 
 ADD confd /etc/confd/
+ADD postmap.sh /start.d/zz-postmap.sh
 
 VOLUME ["/etc/postfix","/ssl","/var/spool/postfix"]
 EXPOSE 25/tcp 587/tcp
diff --git a/postmap.sh b/postmap.sh
new file mode 100755
index 0000000..f022e31
--- /dev/null
+++ b/postmap.sh
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+# run postmap on all configured lookup tables
+
+postconf -h \
+	 postscreen_access_list \
+	 postscreen_dnsbl_reply_map \
+	 smtpd_client_restrictions \
+	 smtpd_helo_restrictions \
+	 smtpd_recipient_restrictions \
+	 virtual_alias_maps \
+	 virtual_mailbox_maps \
+    | sed "s/,/\n/g" | sed "s/ /\n/g" | sort | uniq \
+    | egrep '(hash|ldap|pcre):' \
+    | xargs postmap