Outlook.com and similar are an anathema to email. This is why they tell you not to run a mail server .
On the other hand rejecting domains without dmarc is fine. Just not happy it is silent.
Experience shows that the walls will get taller and the moats will get deeper.
Good for Microsoft customers and I don't care one bit for the lazy people who have to late-patch now.
Go to https://mail-tester.com. Send a test email. If you don't get 10/10, fix your shit.
Also why they do non-standard stuff like accepting mail but then simply not delivering it, rather than bouncing it.
Some can affordably deliver to Microsoft because they aggressively police what they are actually sending on their customers' behalf; others don't get involved and you end up having to spend a fortune on a dedicated IP.
The DMARC thing is just another part of this; one of my clients discovered this silent failure themselves a few weeks back and addressed this.
It doesn't prevent spoofing, it doesn't say which IPs are authorized to send on behalf of a domain, it doesn't sign messages. Spoofed messages are still sendable.
Can you explain the benefit of only accepting email if Microsoft knows that you may or may not accept emails about scammers unsuccessfully spoofing your email domain? (Note, there's nothing you can do if they do tell you.)
Don't confuse DMARC with DKIM or SPF; DMARC doesn't actually do anything for email security.
gmail runs with p=none
so tell me what benefits that has over having no dmarc record at all ?
https://ciphercue.com/blog/dmarc-enforcement-gap-rua-fragmen...
https://news.ycombinator.com/item?id=49081783
I have MCP servers for the creation of domains, DNS records with DNSSEC, and email accounts with SPF, DKIM and DMARC. I'm sure if someone wants to be a professional spammer today, DMARC is not a differentiator.
Company sys admins have likely got all sorts of other issues to worry about, and the occasional report of an email not getting through is likely low on their to-investigate list.
Having said that, I self host a mail server, and have all those things setup correctly, and my workplace uses Outlook, and I've not had issues with delivery, so it's not a particularly difficult bar to jump.
I had kinda assumed that a lot of providers would start rejecting domains without DMARC support. I'm surprised it's happening this late.
When I ran that server, outlook.com was also the only one that would blackhole my email for no known reason. Support was unhelpful and also could not point to any reason. I've since given up, but for a short time it was glorious, email to family would not leave the lan and we could send attachments of arbitrary size.
Is there a risk some people on this thread are mixing up DKIM and DMARC?
DKIM = proving that an email was sent from a specific domain using cryptography. Good for spam fighting and deliverability.
DMARC = telling receivers how to handle mail that fails authentication.
DMARC is primarily useful for large, complex organizations where email admins may not be aware of everyone inside the org who is sending mail that advertises the domain in the From header, or organizations that might be targeted by impersonation attacks (e.g. phishing). Being able to tell recipients "yes we absolutely have our act together so feel free to reject or spamfolder unauthenticated email" is great for killing phishing campaigns, and being able to request reports is great for finding that one sales org that signed up for a guerrilla marketing SaaS that's impersonating them.
But for small personal domains the value isn't that high.
Sounds like kind of a hack:
"ARC was devised to solve this problem by giving intermediate servers a way to sign the original message's validation results. Even if the SPF and DKIM validation fail, the receiving service can choose to validate the ARC chain. If it indicates that the original message passed the SPF and DKIM checks, and the only modifications were made by intermediaries trusted by the receiving service, the receiving service may choose to accept the email."
maybe someone was too lazy to set up "inbound block list" and just did a total blackout instead?
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?
That said checking for these things is a good idea, the only problem I see is dropping the mail on the floor, rather than rejecting it at SMTP time - at least that lets the self-hosting users who haven't got things configured know their email is being rejected, and to pick up the phone instead.
There's nothing worse than sending an email, it being accepted, and then later discarded with no clue to either sender or recipient.
Yes. In the first place, this should not even be a thing. Two corporations should not be in control of who can send e-mail. If they want to mark not having DMARC as spam, mark it as spam, or better yet flag it with a specific warning about the domain, but these games with refusing to deliver are just bullshit and essentially force a monopoly where other e-mail providers cannot compete because their e-mails aren't delivered.
We are literally talking about a situation where this is not happening! And the problem is that it's not just this. Once you give them a license to police e-mail, they start policing e-mail for all kinds of arbitrary and inscrutable reasons. If this were going to be done, it should really be formalized as an industry standard by an independent consortium, not up to the whims of Microsoogle.
DMARC, DKIM and the rest are industry standards set through an independent consortium (it's called the MAAWG iirc)
En contraire, I think not delivering mail is the fastest way to adoption. People will use an old system for as long as it works. It now does not anymore.
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 stops disgusting yourself as a legitimate service.
Allowing basically ~whatever, but proving the sender address is an obviously good approach to me.
Just not for this.
Not true, at least in my experiences.
I have a bunch of email accounts which have SPF and DKIM, but are missing the DMARC line - I've had no deliverability problems at all, until this weekend, and now only with Outlook. Emails to Gmail accounts go through just fine.
The combination of: √ Valid SPF √ Valid DKIM signature X Missing DMARC policy
Is clearly ambiguous. Since a DMARC of "p=none" (in the context of valid SPF and DKIM) really adds no information, so interpreting "missing DMARC" as "p=none" seems reasonable. Sounds like Microsoft was taking that approach until this weekend.
I wonder if there's an actual written standard?
They did: https://techcommunity.microsoft.com/blog/microsoftdefenderfo...
And it appears to be further documented here:
https://learn.microsoft.com/en-us/defender-office-365/anti-p...
https://learn.microsoft.com/en-us/defender-office-365/email-...
And other sites were reporting about it for at least a year and a half:
https://powerdmarc.com/dmarc-outlook-email-authentication/ (see #4)
I had SPF/DKIM set up, just not DMARC. Did that yesterday and don‘t see the point. My policy is "none".
An Outlook user first reaching out to you, and you replying and including the unique message-ID of their original envelope in your headers, doesn't affect anything either. Absurd. The whole situation is complete dog shit.
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.