Admin

Postfix

list postfix mail queue: postqueue -p
view queued mail: postcat -vq <ID>

Largest Directories

du -a ./ | sort -n -r | head -n 20

Firewall

• http://www.cyberciti.biz/faq/how-do-i-block-an-ip-on-my-linux-server/

block IP: iptables -A INPUT -s <IP> -j DROP
block SMTP: iptables -A INPUT -s <IP> -p tcp --destination-port 25 -j DROP

Largest Directories

du -a /var | sort -n -r | head -n 10