Email deliverability: Working with Microsoft's stricter email filters
Microsoft email services like Outlook and Hotmail are bouncing more emails than before. DMARC, which until recently could be reasonably described as optional, is now more like a requirement for Microsoft inboxes.
Anyone sending emails to recipients with inboxes on Microsoft platforms (like Outlook or Hotmail) needs to be aware of a new policy that Microsoft has started enforcing.
We've heard from customers that emails to these platforms are getting blocked or bounced. Luckily, there's a simple fix that anyone sending email can make.
What's Microsoft changed?
It's normal for inbox providers like Microsoft to look for signs that email senders are legitimate. Without these measures, spam would freely flow into email inboxes.
However, we've recently noticed that Microsoft has taken some checks that used to only apply to bulk senders (organisations sending thousands of emails a day, like us) and started applying them much more broadly.
In late September we noticed that Microsoft inboxes were getting harder to reach. Now we've started noticing something similar is happening to smaller email senders.
While blocking spam is important, legitimate email still needs to get through. As a sender, the onus is on you to prove that your emails come from the domain that they claim to come from. Thankfully, there's a fix that ought to get your emails safely getting through to Outlook users.
Updating your DNS records
The specific check that is catching out a lot of email senders is a new requirement for a DMARC record, a DNS record that applies specifically to your email domain.
If, for example, emails from sales@example.com aren't getting through to Outlook, then you need to make an update to DNS settings for example.com.
DMARC records are one of three DNS record types that work together to prove that your emails are coming from a legitimate sender. Back in 2024 we blogged about SPF, DKIM and DMARC when Gmail tightened up its email filters. Back then we could safely say that DMARC records were usually optional. That's no longer the case.
The specific DNS record to add is a TXT record:
Name:
_dmarcValue:
v=DMARC1; p=none
If your domain is with SiteHost, our Knowledge Base has instructions for adding a new DMARC record. If your domain is held elsewhere, you'll need to log into that domain management platform to make the DNS update.
The war against spam never ends
Different email platforms use different spam detection methods. Over time these methods will evolve. As a sender, it's important to conform closely to standards like SPF, DKIM and DMARC. Doing so will make future changes less likely to create issues.
The most recent step in this fight again spam is Microsoft enforcing DMARC. Thankfully, for you as an email sender, one small change ought to be enough to stay on top of this change.