Deliverability is arguably a cornerstone factor for most businesses that rely on email marketing, transactional messages, or any form of email communication. Microsoft (which powers Outlook, Hotmail, Live, and MSN) employs strict spam filters. To help legitimate senders monitor their performance, Microsoft offers the Smart Network Data Services (SNDS) platform.
In this blog, we’ll explore what SNDS is, the key metrics it can provide, and best practices to maintain a strong sending reputation with Microsoft’s services. By following these guidelines, you can improve inbox placement and avoid being flagged, throttled, or even blocked.
SNDS is a free analytics tool designed to help email senders monitor their performance across Microsoft’s network. It provides guidance for how Microsoft’s spam filters are handling your mail, allowing you to identify and resolve potential issues before they hurt your overall deliverability.
To start using SNDS, first sign up at snds.microsoft.com. After registering, add your sending IP addresses to track their reputation. Microsoft may require verification to confirm IP ownership and may ask for documentation. Once your request is approved, you’ll gain access to detailed reports that provide insights into your email deliverability status and sender reputation.
SNDS provides several important metrics that influence your reputation:
1. IP & Domain Reputation
Microsoft categorizes your sending reputation into three levels. Green indicates good standing and that your emails usually land in inboxes. Yellow signals potential issues and that some emails may be diverted to spam. Red points to poor reputation, with a high likelihood of being marked as spam or blocked entirely. If your reputation shifts to yellow or red, investigate and address the underlying issues immediately.
2. Spam Complaint Rate (SCR)
Microsoft monitors its Spam Complaint Rate closely. This measures how frequently recipients mark your email as spam. A high complaint rate raises red flags with Microsoft’s filtering systems. Best practices recommend keeping SCR below 0.1%, or no more than one complaint per 1,000 emails sent. Provide clear, easy unsubscribe options and ensure subject lines accurately reflect the content.
3. Filtered Percentage
This metric shows how many of your emails are sent to the Junk folder instead of the inbox. A sudden increase suggests deliverability problems.
4. Trap Hits
Microsoft uses spam traps to identify poor list hygiene. Hitting these traps severely damages your reputation. Regularly clean your sending lists and remove inactive subscribers.
5. Volume & Traffic Trends
Monitoring email volume and traffic trends is important for maintaining good deliverability with Microsoft. Sudden, unexpected spikes in sending volume can raise red flags and cause mail to be blocked or diverted to junk. Maintain steady, consistent sending volumes. When scaling campaigns, increase gradually so Microsoft’s systems recognize your sending patterns as legitimate.
To help your emails reach the inbox, follow these proven strategies:
1. Implement Proper Email Authentication
Microsoft prioritizes authenticated emails. Ensure you have SPF (Sender Policy Framework) to verify authorized sending IPs, DKIM (DomainKeys Identified Mail) to add a digital signature proving email integrity, and DMARC (Domain-based Message Authentication, Reporting & Conformance) to tell Microsoft what to do if authentication fails. A strict DMARC p=reject policy improves trust with Microsoft.
2. Maintain a Clean Email List
Sending to invalid or inactive addresses hurts your reputation. Use double opt-in to confirm subscriber consent, remove hard bounces immediately, and regularly prune inactive subscribers with no opens or clicks in six months or more.
3. Minimize Spam Complaints
High complaint rates lead to filtering. Provide a clear, one-click unsubscribe option, avoid deceptive subject lines, and segment lists to send more relevant content.
4. Warm Up New IPs Gradually
New IPs with sudden high volume look suspicious. Start with low volumes and increase sending gradually, averaging around four to six weeks.
5. Monitor SNDS & Test Email Placement
Check SNDS daily for reputation changes. Send test emails to Outlook accounts and check whether they land in the Inbox or Junk.
6. Avoid Spammy Content & Improve Engagement
Low engagement, including poor open and click rates, signals spam risk. Personalize emails when possible and avoid excessive promotional language.
7. Handle Bounces Properly
Remove hard bounces (permanent failures). Soft bounces (temporary issues) should be retried, but paused if persistent.
If your SNDS dashboard shows a decline, pause sending from affected IPs, audit your email list for spam traps or inactive users, check SPF/DKIM/DMARC for errors, and request a review through Microsoft’s Junk Mail Reporting Program.
SNDS is an extremely important tool for any business sending email to Outlook, Hotmail, or MSN users. You can proactively maintain a strong sender reputation. Following best practices, such as proper authentication, list hygiene, and gradual IP warming, will help you avoid spam filters and maximize inbox placement. By staying vigilant and optimizing your email practices, you can create the best opportunity for reliable deliverability across Microsoft’s systems.
