diff --git a/emailwiz.sh b/emailwiz.sh
index faa1a6d..e9fb562 100755
--- a/emailwiz.sh
+++ b/emailwiz.sh
@@ -94,7 +94,7 @@ postconf -e 'smtpd_sasl_type = dovecot'
 postconf -e 'smtpd_sasl_path = private/auth'
 
 # Sender and recipient restrictions
-postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination'
+postconf -e 'smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination, reject_unknown_recipient_domain'
 
 # NOTE: the trailing slash here, or for any directory name in the home_mailbox
 # command, is necessary as it distinguishes a maildir (which is the actual