This might be useful to let some less-certain spam detection to put things into the Spam folder, but hide the more obvious stuff completely.
This is the one I installed in the 90's on my home machine, and used in conjunction with fetchmail to retrieve messages over POP. Always the rebel, I had to try something besides mail and pine, and elm seemed too similar to both.
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[LetsEncrypt and ZeroSSL certificates are only for domain validation (web/server encryption).]
You can upload your own certificate.
Looks like the secret sauce is DANE, a.k.a. opportunistic TLS.
In 2022, enabling it seems to help with getting filtered as spam by Google servers.
I just put addresses in the file specified by check_recipient_access with REJECT
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getting mail lists and DKIM to play together
requires Linux and runs DNS and Postfix in a Docker node
This is really annoying here at PSU.
