Microsoft requires DMARC for consumer domains and what it means for you
Thomas Hampel
6 April 2025These days a number of customers are reaching out to us due to Microsoft's announcement to make DMARC mandatory.
Customers are afraid of their mails getting lost because Domino does not provide native DMARC support yet.
For outbound mails, DMARC just describes what a recipient server should do with an email.
By using a DNS TXT record in YOUR DNS, the recipient is instructued to do: Nothing, Quarantine, or Reject an email from a sender that does not meet your SPF record and doesnt provide a DKIM signature.
Sounds easy (+is easy) for Domino customers to set up - details at the end of this post
How will Microsoft's announcement affect you?
Let's take a look at the facts first:
- Microsoft's announcement will affect CONSUMER domains (=hotmail.com, live.com, outlook.com), but not other domains.
- Even after May 5th 2025, Microsoft will not reject your mails.
- Non compliant high volume senders (to consumer domains!) will find mails ending up in the junk folder of the recipient.
- A typical O365/Exchange Onprem customer using @YourDomain.com is not affected, for clarification see this official comment from Microsoft
This all is nothing new. Google also announced the same same, and it is in effect since February 1, 2024
Are you sending more than 5.000 mails PER DAY to @hotmail.com, @live.com, or @outlook.com or likewise for @gmail or @googlemail.com accounts?
Then you are a considered being a bulk sender!
Bulk messages often are marketing campaigns, targeting individuals only using generic MS or Google domains listed above. Essentially being B2C mailings.
You can still send mails to folks using those email domains. Just if your company sends more than 5.000 mails in a single day your mail might be put into the Junk folder if you have not added a DMARC record.
By the way, for marketing initiatives, mass mailings, etc, take a look at products like HCL Unica
However, if you want Domino to meet the DMARC requirements, all you have to do is to enable DMARC in DNS.
A prerequisite is having configured SPF and DKIM, both are standards Domino supports.
With those prerequisites being configured, enabling DMARC is quite simple.
For details see step by step instructions in this article and once done, run a DMARC check against your domain.
If you are looking for a Domino application to analyze DMARC Inbound reports, take a look at this template from NTF-Factory
As a side note:
Microsoft Exchange (onprem) does neither support DKIM nor DMARC - both would require 3rd party products (see this).
References:
- What is DMARC ?
- Ideas portal: DMARC Support for Domino
- Google's Announcement - effective Feb 1st 2024
- Microsoft's Announcement - effective May 5th 2025
- KB0103502 - Whitepaper: Understanding SMTP authentication and using DKIM and SPF
Tagged with: Mail