"Since November 5, 2026, Microsoft's consumer mail service has been turning away some of the email from domains that don't publish a DMARC record. If your company emails customers, vendors or applicants with outlook.com, hotmail.com, live.com or msn.com addresses, some of that mail may be bouncing right now. Nobody announced it. The fix is one DNS record."

I'm personally seeing this with some email systems I manage - email sent from a domain that has proper SPF and DKIM signatures, but had no DMARC record started bouncing this weekend.

I actually totally agree with this. There's too much risk involved with scams disguised as legitimate services because the developers of said service couldn't be bothered to add 1 or 2 dns records.

Although there seems that there hasn't been any communication which is the bad thing here. However, nobody looks at those and sending detailed emails back seems like a good enough solution.

This is interesting. At some point, I think it'll be desirable to give increasing positive weight to emails with the DPF/DKIM/DMARC trifecta configured, since those are least likely to be problem emails (spam or phishing), but I wonder what the best avenue is to actually make that the default. It's almost certainly not this kind of unannounced cutoff.

Email is, I think, among the most distributed popular online services, and there's a ton of stuff that's legacy, self-managed, or otherwise janky. Supporting SPF, DKIM, and DMARC does put a burden on independent operators, but is it an undue or unreasonable one in the current landscape? Or is it just the new cost of doing business?

I noticed this when it happened, but I do have a valid DMARC entry (albeit p=quarantine).

https://mastodon.social/@davisr/117570496362439342