If you do want to “fight” spammers, SpamCop is probably the best bet. It’s not perfect, but it’s very good. Just make sure to read the instructions.
As to email authentication standards …
No. And yet, inevitably, yes. They’re all fundamentally wrong by design, and yet they are the saviour of email by popular decree. Use them if you must, and if you can, and if your soul will permit. I’ll rant further on request, but the crucial thing is that the DMARC reporting facility will help you identify any problems before you go live. (I don’t think Tidbits has anything to worry about, because it never sends mail from anywhere other than tidbits.com . In particular, it is not a mailing list operator, and it is not expected to send mail through other mailing lists, so all its mail can originate from and be signed by its mailer. There are a few, very small, number of corner cases related to conversion of mail by email gateways, but they are vanishingly rare, in practice.)