The other day, I realized that from time to time, alpine, my console mail client for about 20+ years now, would close the connection to the IMAP server because of an “error”. Digging in the logs, I realized my server was being bruteforced for months, if not years. NetBSD being the fantastic OS it is, it actually had nearly no effect on my server’s behaviour, only those annoying connections closing from time to time.
I have read a shitload of overcomplicated setups to bring up a postfix / dspam SMTP + antispam server, and finally came to a much lighter and simpler configuration by basically reading documentation and real life examples. Note this is suitable for a personnal and basic environment, no database, no virtual setup. Basic stuff. The target system is NetBSD but this short doc should apply to pretty much any UNIX / Linux.