diff --git a/install/vst-install-debian.sh b/install/vst-install-debian.sh
index 4f7aa770..87edd88b 100644
--- a/install/vst-install-debian.sh
+++ b/install/vst-install-debian.sh
@@ -1079,7 +1079,9 @@ if [ "$dovecot" = 'yes' ]; then
     cp -rf $vestacp/dovecot /etc/
     cp -f $vestacp/logrotate/dovecot /etc/logrotate.d/
     chown -R root:root /etc/dovecot*
-    sed -i "s#namespace inbox {#namespace inbox {\n  inbox = yes#" /etc/dovecot/conf.d/15-mailboxes.conf
+    if [ "$release" -eq 9 ]; then
+        sed -i "s#namespace inbox {#namespace inbox {\n  inbox = yes#" /etc/dovecot/conf.d/15-mailboxes.conf
+    fi
     update-rc.d dovecot defaults
     service dovecot start
     check_result $? "dovecot start failed"