Fix Dovecot Connection

Fix dovecot Connection

install/ubuntu/16.04/dovecot/dovecot.conf

@@ -3,7 +3,7 @@ listen = *, ::
 base_dir = /var/run/dovecot/
 !include conf.d/*.conf
 
-namespace {
+namespace inbox{
     type = private
     separator = /
     prefix =