Microsoft has made some significant changes to their email service and infrastructure this year. A lot of these changes involve improving and modernizing their backend systems. These changes should be more or less seamless for senders. However, they have also made some changes that will impact senders and end-users alike.

Who is affected by the changes?

If you are a sender who closely monitors your spam report statistics (if you aren’t doing this, you should be) you may have noticed a sharp increase in the number of spam reports you are receiving from Microsoft domains such as,,, etc.

If you’ve seen this trend and you are wondering why so many more people seem to not like your messages anymore, fear not. Most senders are seeing the same thing. Why? Because many Microsoft mail clients have an updated UI.

Consequently, Microsoft has added “Report Junk” buttons to all of their mobile clients.

They have also added some back-end functionality that will trigger a spam report if a user moves a message from the inbox to the junk folder—we have heard this referred to as “implicit junk reporting.”

This is a hugely impactful change because, according to Litmus, at present, roughly 54% of all email engagement comes from mobile devices. This means that about 54% of your spam reports have potentially gone unreported.

What should I do about this?

Senders do not need to take any immediate action as a result of these changes. It is safe to assume that Microsoft’s spam filters have always been capturing this feedback. The only change is that they are now presenting it to senders.

The best thing you can do is ensure you are consuming data (using the spam forwarding app, or consuming spam report events from our Event Webhook).

If you are already doing that, you should be reviewing your spam report data and looking for ways to use that information to improve your email program.

Look for campaigns or mail streams that are generating a disproportionate number of spam reports and figure out why. Some explanations might include:

Whatever the case may be, tracking spam report trends is an important part of building and maintaining a healthy email program. Smart senders will use this extra spam report data to further improve the recipient experience and drive even better results from their email marketing efforts.

Check out SendGrid’s Email Delivery Best Practice Guide to brush up on all the information and insight you need to ensure that your email goes into the inbox and not the spam folder.

Luke is a deliverability expert with a passion for getting email to the inbox. His intimate understanding of the email ecosystem, email protocols, and marketing best practices allows him to provide data and insights that drive engagement and results from email programs both large and small.