Hacker News, a #CyberSecurity newsletter, is sent from a domain where DMARC policy is p=none, which tells email providers, like gmail, to deliver all email that is screaming, "I am a Hacker News spoof email sent by a POS scammer" to the intended recipient anyway. p=none means take no action, even if you know it's a scam. Spam folder optional. Email services and clients will oblige. WTF Hacker News?
Hacker News is also using an insecure signature algorithm for signing their newsletter.
An extremely well-known Cybersecurity expert is sending the newsletter from a domain that has no DMARC record at all, so all spoof emails claiming to be from them will be delivered. And likely this is being constantly exploited. A DMARC policy of p="reject" would have those spoof emails trashed and not delivered. But no DMARC policy means "whatever, and I don't want to know". So, spoof emails go through unstopped and no reports of abuse are being sent to this person either. And it's their job to tell us how to stay secure and not be fooled by spoof emails. WTF?
Sometimes I don't understand how things work in the world.
Important reminder, if you own a domain name and don't use it for sending email.
There is nothing to stop scammers from sending email claiming to be coming from your domain. And the older it gets, the more valuable it is for spoofing. It could eventually damage your domain's reputation and maybe get it blacklisted, unless you take the steps to notify email servers that any email received claiming to come from your domain should be trashed.
Just add these two TXT records to the DNS for your domain:
TXT v=spf1 -all
TXT v=DMARC1; p=reject;
The first says there is not a single SMTP server on earth authorized to send email on behalf of your domain. The second says that any email that says otherwise should be trashed.
If you do use your domain for sending email, be sure to add 3 records:
SPF record to indicate which SMTP server(s) are allowed to send your email.
DKIM records to add a digital signature to emails, allowing the receiving server to verify the sender and ensure message integrity.
DMARC record that tells the receiving email server how to handle email that fails either check.
You cannot stop scammers from sending email claiming to be from your domain, any more than you can prevent people from using your home address as a return address on a mailed letter. But, you can protect both your domain and intended scam victims by adding appropriate DNS records.