On Sun August 9 2020 15:52:37 David C. Rankin wrote: > # iptables -nvL --line-numbers > Chain INPUT (policy ACCEPT 3651K packets, 548M bytes) > num pkts bytes target prot opt in out source > destination > 11 3074 182K DROP all -- * * 37.0.0.0/8 > 0.0.0.0/0 Dang. I checked as much as I could of your SMTP and even checked BGP looking glasses but of course I couldn't see your iptables! You might want to try rate limiting, connection limiting, and fail2ban instead of hard iptables blocks. --Mike