> lmtp_destination_concurrency_limit = 20 > lmtp_destination_recipient_limit = 300 > Should I rise both limits to 1200? I'm sorry, I only remember now of http://cyrusimap.org/docs/cyrus-imapd/2.4.17/install-configure.php If this is right I have to modify only lmtp_destination_recipient_limit. Thank you again Marco