For reference
This is an old revision of the document!
https://www.seenlyst.com/blog/geo-blocking-ufw-iptables/ https://blog.reverside.ch/UFW-GeoIP-and-how-to-get-there/
IPtables https://ithelp.ithome.com.tw/articles/10312284
Digitalocean benchmark
CPU + Disk IO
Memory
find /home/jwcorner/mail/jwcorner.com/noreply/ -type d \( -name cur -o -name new \) -exec find {} -mtime +1 -type f -delete \;