I got myself a VPS just in case. Setting up the mail server turned out to be very fun and exciting :)
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It's fun and educational because:
0) #DragonFlyBSD
1) vpn
2) ipv4 + ipv6 (WIP)
3) encrypted root partition
4) a mail server with all the whistles and fakes (spf, dkim, dmarc ...)
5) secure dns, well, this is at the very beginning of the process, I have no idea about dns management.
Great, I've tried and run pretty much everything except passing the ip 6 through the ip 4 tunnel. 🙂
I even learned about DNSKEY, RRSIG, NSEC3 and DS records, generated keys and signed my zone. And then I discovered that my dns provider does not support DNSSEC🤣
There is no point in buying a dns hosting for a training server, let it work for a couple of months, I will look at its reliability.