Sending to Outlook.com Users gets more complicated

The arms race between spammers and Inbox Providers continues with Microsoft’s recent announcement of changes to Outlook.com bulk emailer rules. Fortunately, there is good news:

If you have already committed to Google and Yahoo Bulk Sender requirements, you are already covered. Keep doing what you are doing!

What are the specifics?

On May 5, 2025 you will be required to meet the following requirements to make the inbox when emailing Microsoft users (Office 365, Outlook, Hotmail):

  1. Authentication: All emails must pass SPF, DKIM, and DMARC to be delivered to Microsoft inboxes.
  2. Bulk email: Newsletters, surveys, and other marketing emails must allow recipients to opt-out and must support functional one-click unsubscribe. Plus, unsubscribe requests need to be processed within 48 hours. Remember, if you send more than 5,000 messages in a month, you will automatically be labeled a bulk sender.
  3. Sender addresses: Ensure your “From” or “Reply-To” address is valid and compliant, displays the actual sending domain, and can receive reply emails.
  4. List hygiene: Routinely review and update your recipient list to make sure your messages are NOT being sent to addresses that bounce or label your email as spam. Keeping a healthy marketing email list is vital to maintain a high delivery rate and sender reputation.

How Can MxToolbox Help?

MxToolbox’s Delivery Center helps you manage the complexities of DMARC Configuration and Management . Our comprehensive email delivery tools allow you to setup SPF, DKIM, and DMARC, implement a DMARC “reject” policy, maintain compatibility with changing Google, Yahoo! and Outlook.com sender requirements and manage emerging delivery issues.

A major tool in our suite of email delivery tools, Inbox Placement, allows you to test your outgoing email campaigns for over 50 different delivery issues, and notifies you if your campaigns are likely to go to the Spam/Junk folders or achieve the Inbox. In addition, Delivery Center Inbox Placement your Google spam rate and ensures tests that your campaigns meet one-click unsubscribe requirements at Google, Yahoo! and Microsoft Outlook.com.

MxToolbox is the Expert on email delivery. We offer a wide range of email delivery services, including a fully managed email delivery service, so be proactive now and take advantage of them before these Bulk Sender guidelines affect your email.