diff --git a/setup/mail-postfix.sh b/setup/mail-postfix.sh
index 5787e8c9..7308458e 100755
--- a/setup/mail-postfix.sh
+++ b/setup/mail-postfix.sh
@@ -56,7 +56,7 @@ apt_install postfix postfix-sqlite postfix-pcre postgrey ca-certificates
 tools/editconf.py /etc/postfix/main.cf \
 	inet_interfaces=all \
 	smtp_bind_address=$PRIVATE_IP \
-	smtp_bind_address6=$PRIVATE_IPV6 \
+	smtp_bind_address6=$PUBLIC_IPV6 \
 	myhostname=$PRIMARY_HOSTNAME\
 	smtpd_banner="\$myhostname ESMTP Hi, I'm a Mail-in-a-Box (Ubuntu/Postfix; see https://mailinabox.email/)" \
 	mydestination=localhost