DNSSEC and TLSA PoC Site
FAQ - How does it work?
Here are some basic information links:
Why do I need DNSSEC
DNSSEC online test for clients
How to enable DNSSEC validation on my DNS servers
DNSSEC Server online checking
DNSSEC Documents and RFCs
DANE Documents and RFCs
DANE/TLSA Sample pages
SMIMEA Test pages
Current commercial mailgateway products supporting RFC8162
You can use any "classic" SMIME capable mailgateway to decrypt inbound mails which were encrypted using your SMIMEA key from DNS.
However, you need an RFC8182 capable mailgateway to encrypt outbound mails to mailpartners who publish their SMIMEA key in DNS.