What are the limitations of Amazon SES regarding Microsoft SNDS access and is there a workaround?
Matthew Whittaker
Co-founder & CTO, Suped
Published 7 May 2025
Updated 19 Aug 2025
6 min read
When managing email deliverability, gaining full visibility into how major mailbox providers perceive your sending reputation is critical. For many senders using Amazon Simple Email Service (SES), a common question arises regarding access to Microsoft's SNDS (Sender Network Data Services) program. This platform provides invaluable insights into your IP's health within the Outlook.com ecosystem, including Hotmail and Live.com.
However, it's not always straightforward. I've encountered many situations where senders using dedicated IPs with Amazon SES face limitations in directly accessing SNDS data. This can be frustrating, especially when you need granular detail to troubleshoot deliverability issues or manage your sending reputation proactively.
The challenge of direct SNDS access
The core limitation with Amazon SES and Microsoft SNDS stems from Amazon's security policy. When you lease a dedicated IP address from SES, you don't actually own that IP. Amazon retains ownership, and these IPs are recycled and reassigned to other SES customers over time. This dynamic IP management model creates a security challenge for direct SNDS access. If a previous owner of an IP had direct SNDS access, they could potentially view the sending data of a new customer once the IP is reassigned, posing a significant data privacy risk.
Because of this, Amazon SES does not support the addition of their leased dedicated IPs to the Microsoft SNDS program for direct customer verification. This is a deliberate policy designed to safeguard customer data and prevent unauthorized access to sensitive sending statistics. While it's understandable from a security standpoint, it can certainly be frustrating for email senders who rely heavily on such data for managing their email programs.
This policy means that you cannot log into the SNDS portal yourself and register your Amazon SES dedicated IP addresses. Other email service providers (ESPs) might offer direct SNDS access or manage it on your behalf, but with SES, the approach is different due to their unique infrastructure and IP management. This difference can lead to questions about how to effectively monitor and improve your standing with Microsoft receiving domains.
Amazon SES's workaround: CloudWatch metrics
To mitigate the lack of direct customer SNDS access, Amazon SES has established a partnership with Outlook.com. This collaboration allows Amazon to receive a subset of SNDS data for the dedicated IP addresses it leases to customers. This data is then made available to you through Amazon CloudWatch, Amazon's monitoring service.
This workaround provides some insight into your IP's sending behavior and can flag potential issues affecting your sender reputation. The key data points you can typically access via CloudWatch metrics for dedicated IPs include:
SNDS.RCPTCommands: The number of SMTP RCPT commands your IP received.
SNDS.DATACommands: The number of SMTP DATA commands received.
SNDS.MessageRecipients: Total recipients for messages sent from your IP.
SNDS.SpamRate: The rate at which your mail is being marked as spam.
SNDS.ComplaintRate: The rate of user complaints for your emails.
SNDS.TrapHits: Instances where your emails hit a spam trap.
These metrics are helpful for a general overview, but they don't provide the granular, real-time feedback that direct SNDS access offers. It's a compromise, trading full visibility for Amazon's stringent security protocols.
Why direct SNDS data is crucial for deliverability
While the CloudWatch metrics provide a good starting point, many deliverability professionals (myself included) find the limited data challenging. The full SNDS portal offers more detailed insights that are crucial for deep-diving into issues and proactive reputation management. For instance, direct SNDS access provides sample MAIL FROM addresses, precise activity periods, and trap message periods. These data points can be incredibly useful for pinpointing the exact campaigns or segments causing reputation damage.
Individual spam complaints are another vital piece of information missing from the CloudWatch feed. Having access to these can help identify specific issues, understand user behavior, and debug potential delays or throttling imposed by Microsoft, often by examining email headers. Without this granular data, it becomes harder to diagnose the root cause of deliverability problems, especially when emails are landing in the spam folder or being blocked entirely.
This limited visibility can make it challenging to maintain an optimal sending reputation with Microsoft properties. While Amazon SES itself has excellent deliverability infrastructure, the inability to directly leverage SNDS for detailed analysis means senders must rely on other signals and proactive measures to ensure strong inbox placement.
Strategies for managing Microsoft deliverability with SES
Despite the limitations, it's certainly possible to achieve excellent deliverability with Amazon SES even without direct SNDS access. The key lies in robust best practices and leveraging alternative monitoring tools. Here are some strategies:
Proactive steps
Strong authentication: Ensure your SPF, DKIM, and DMARC records are perfectly configured and aligned. This is fundamental for building trust with mailbox providers, including Microsoft.
List hygiene: Regularly clean your email lists to remove inactive users, bounces, and potential spam traps. A clean list significantly reduces complaint rates and improves sender reputation.
Engaging content: Send relevant and engaging content to maintain high open and click rates, and low complaint rates. User engagement is a strong positive signal to mailbox providers.
Monitoring and response
CloudWatch metrics: Actively monitor the SNDS data available in CloudWatch. Set up alerts for any spikes in spam or complaint rates that could indicate a problem.
Complaint feedback loops (FBLs): Ensure your SES account is configured to receive complaint feedback loop data. This allows you to immediately remove users who mark your emails as spam, minimizing future issues.
Blocklist monitoring: Regularly check if your dedicated IPs or sending domains are listed on any major blocklists (blacklists). Being blocklisted can severely impact your deliverability to all providers.
While you might not get the same level of detail as direct SNDS access, a combination of these strategies will provide a comprehensive approach to email deliverability management and help ensure your messages consistently reach the inbox.
Views from the trenches
Best practices
Maintain a pristine email list to minimize bounces and complaints, especially with Microsoft recipients.
Regularly check your IP and domain reputation through available tools and CloudWatch metrics.
Implement and monitor DMARC, SPF, and DKIM for all sending domains.
Ensure prompt removal of subscribers who mark your emails as spam using feedback loops.
Warm up new dedicated IPs slowly and consistently to build a positive sending history.
Common pitfalls
Assuming good deliverability without actively monitoring CloudWatch metrics.
Not cleaning inactive or unengaged subscribers, leading to higher complaint rates.
Ignoring feedback loop data from Microsoft, which can lead to blocklists.
Sending inconsistent email volumes or types from dedicated IPs.
Neglecting proper email authentication (SPF, DKIM, DMARC) for Microsoft compliance.
Expert tips
Utilize Amazon CloudWatch alarms to notify you immediately of any spikes in complaint or spam rates.
Cross-reference CloudWatch data with other deliverability tools for a more complete picture.
Focus on content quality and subscriber engagement, as these are strong signals to Microsoft's filters.
Segment your audience and tailor content to reduce the likelihood of spam complaints.
If using shared IPs initially, ensure you migrate to dedicated IPs when your sending volume justifies it.
Expert view
Expert from Email Geeks says that the lack of direct SNDS access is simply Amazon's policy, and there is no way to force them to change it.
2022-06-28 - Email Geeks
Marketer view
Marketer from Email Geeks says that the partial data provided via CloudWatch is a downside, and it makes them less inclined to choose Amazon SES over other providers in the future.
2022-06-29 - Email Geeks
Navigating deliverability with SES
While Amazon SES's policy on direct Microsoft SNDS access may seem like a limitation, it's a measure rooted in their robust security framework to protect customer data. The alternative, receiving SNDS data via CloudWatch, provides essential reputation insights, even if it lacks the granular detail of the direct portal.
Ultimately, successful email deliverability with Amazon SES relies on a holistic approach. By combining the available CloudWatch metrics with diligent list management, proper authentication (DMARC, SPF, DKIM), and a strong focus on sending engaging content, you can maintain a healthy sender reputation and consistently reach the inboxes of Microsoft recipients. Proactive monitoring and adherence to best practices will always be your strongest allies in the complex world of email deliverability.
Outlook.com ecosystem, including Hotmail and Live.com.
Microsoft SNDS stems from Amazon's security policy. When you lease a dedicated IP address from SES, you don't actually own that IP. Amazon retains ownership, and these IPs are recycled and reassigned to other SES customers over time. This dynamic IP management model creates a security challenge for direct SNDS access. If a previous owner of an IP had direct SNDS access, they could potentially view the sending data of a new customer once the IP is reassigned, posing a significant data privacy risk.
Outlook.com. This collaboration allows Amazon to receive a subset of SNDS data for the dedicated IP addresses it leases to customers. This data is then made available to you through Amazon CloudWatch, Amazon's monitoring service.
