Yeah: o SMTP = postfix/exim/sendmail (hint don't use the last two) o dkim, spf & reverse-dns are just DNS records. Spf is a list of IPs that your domain "owns

Yeah: o SMTP = postfix/exim/sendmail (hint don't use the last two) o dkim, spf & reverse-dns are just DNS records. Spf is a list of IPs that your domain "owns", dkim is a hash that proves you own the originating server. o Log parsing is standard log interrogation stuff. You are better off writing a custom metrics exporter that talks to the queue than parse logs routinely. o Greylisting is a configuration option for email relays where they reject the first attempt of unknown servers attempting to deliver mail. nothing more to it. (https://www.greylisting.org/implementations/postfix.php https://www.greylisting.org/implementations/postfix.php) o rate-limiting is again a config option: https://www.vooservers.com/technical-blog/rate-limit-outbound-mail-in-postfix/ https://www.vooservers.com/technical-blog/rate-limit-outboun... o spam filtering: https://docs.iredmail.org/enable.dnsbl.html https://docs.iredmail.org/enable.dnsbl.html is a good start