Last Updated: 03/03/2026
Some clients are experiencing increased email delivery blocks when sending to Microsoft consumer addresses such as Outlook.com, Hotmail.com, and Live.com. These blocks may be due to recent changes in Microsoft’s filtering systems. We are actively monitoring the situation and working with SendGrid, our email delivery provider, to help ensure smooth delivery.
What’s Happening?
According to SendGrid, Microsoft implemented stricter reputation-based filtering which has resulted in an increase in blocked emails. This issue is affecting senders across multiple platforms.
Recommended Actions
To monitor your sending reputation, SendGrid recommends registering your sending IP with Microsoft Smart Network Data Services (SNDS) at https://postmaster.live.com/snds/. Our Core iQ support desk can provide your sending IP if you do not know it.
Benefits of SNDS:
- Monitor how Microsoft views your sending reputation
- Identify spam complaints or filtering trends
- Track potential issues specific to Microsoft domains
Please note, Microsoft requires an Outlook.com, Hotmail.com, or Live.com email address to register. If your organization does not have one, you can create a dedicated account for SNDS access. This account can be used internally solely for monitoring deliverability.
If blocks persist after SNDS registration, SendGrid recommends opening a Microsoft Support Request:
- Visit Microsoft Support at https://olcsupport.office.com/
- Follow prompts to submit a support ticket
- Note the ticket number and submission date
- Monitor the ticket for responses and updates
Best Practices for Deliverability
While Microsoft’s filtering changes may have increased the number of blocked emails, strong sending practices can help maintain and improve deliverability:
- Send only to opted-in recipients
- Regularly clean inactive contacts from your lists
- Avoid large, sudden spikes in send volume
- Monitor engagement metrics such as opens, clicks, and unsubscribes
If you have any questions about Microsoft email delivery or the recommended actions, feel free to reach out to our support team at support@onovative.com.