I used to use this very nice tool:
https://a-s-k.sourceforge.net/
... which was a very simple challenge/response "prove you are a human by
responding to this test email and then be whitelisted in the future":
https://a-s-k.sourceforge.net/howitworks.html
... anyway, ASK has been deprecated since 2016.
Before I attempt to rewrite, or update, this tool (or worse, run it as-is,
unchanged since 2016) I wonder if there are any existing solutions for
modern-day OpenSMTPd that do something similar ?
Thanks.
