Email deliverability: How to get through Microsoft's stricter email filters

If you send emails to recipients with inboxes on Microsoft platforms like Outlook or Hotmail, you need to be aware of a new policy that Microsoft has started to enforce. We are hearing from customers that emails to these platforms are getting blocked or bounced, but luckily there is an easy fix that email senders can make.

What has Microsoft changed?

To prevent spam, it's normal for inbox providers like Microsoft to look for signs that email senders are legitimate. Microsoft has taken some checks that used to only apply to bulk senders (i.e. organisations sending thousands of emails a day) and started applying them much more broadly.

We are a bulk sender, and in late September we noticed that Microsoft inboxes were getting harder to reach. Today, something similar is happening to smaller email senders.

Blocking spam is important, but legitimate email still needs to get through. As a sender, you need to prove that your emails are coming from the domain that they say they are coming from. Luckily, there's a fix that ought to get you back in Microsoft's good books.

Update your email domain's DNS records

The specific check that is catching out a lot of email senders is a new requirement for something called a DMARC record (it stands for "Domain-based Message Authentication, Reporting & Conformance"). This is a DNS record which applies to your email domain - so, for example, if emails from [email protected] aren't getting through to Outlook, then you need to make an update to DNS settings for example.com.

DMARC records are one of a trio of DNS record types that work together to prove that your emails are coming from a legitimate sender. We blogged about SPF, DKIM and DMARC in 2024, when Gmail tightened up email filters. Back then we could safely say that DMARC records were usually optional. That is no longer the case.

The specific DNS record to add is a TXT record:

• Name: _dmarc
• Value: v=DMARC1; p=none

If your domain is with MyHost, our Knowledge Base describes exactly how to add 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.

If you do not already have SPF and DKIM records, now is the perfect time to add those as well. If your domain is with us, the Knowledge Base can help with SPF records and DKIM records as well.

The fight against spam will continue

Different email platforms, like Outlook or Gmail, have 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. That way, future changes are less likely to catch you out.

Microsoft's new use of DMARC is another step in the fight against spam. For you as an email sender, one small change ought to be enough to handle it.