Outlook.com Is Quietly Rejecting Email from Domains Without DMARC

Re:Outlook.com Is Quietly Rejecting Email from Domains Witho... by drdaeman on Sunday November 08, 2026 @06:53PM (#50419069)

There is a trick. Sign up with them, configure custom domain, but don’t set your MX records. On your MTA, route mail that goes to Outlook/Hotmail to go through their MSA with your Outlook credentials and headers stripped as if submitted directly by user. Outlook gets mail through their own MSA it trusts, rest of the world talks to your mail system directly.

I haven’t productionized this setup (I send maybe a dozen emails a year) but it worked for me a couple years back, when I had to send a mail to an Outlook-hosted address and they blackholed everything I tried to send while 250 OKing me.

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Re:Outlook.com Is Quietly Rejecting Email from Domains Witho... by unixhero on Monday November 09, 2026 @01:05AM (#50421641)

Great idea

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Re:Outlook.com Is Quietly Rejecting Email from Domains Witho... by litoE on Monday November 09, 2026 @01:13AM (#50421697)

The problem with this setup is that if I want to send email to [email protected] and example.com is actually handled by Outlook, I need to somehow know beforehand that email to example.com needs that special routing. Or do you just route ALL your outbound email through Outlooks MSA?

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Re:Outlook.com Is Quietly Rejecting Email from Domains Witho... by danielheath on Monday November 09, 2026 @02:19AM (#50422159)

Pretty easy to tell whether example.com uses outlook; it'll have MX records pointing there.

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Re:Outlook.com Is Quietly Rejecting Email from Domains Witho... by jeroenhd on Monday November 09, 2026 @06:00AM (#50423934)

You can usually figure that out by checking the MX records (though some spam filtering middlemen might make that hard to detect) and TXT records (if a domain imports Outlook's SPF list, it's probably on Outlook in the back).

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