What to do when Microsoft's SNDS IP review auto-reply is received?
Matthew Whittaker
Co-founder & CTO, Suped
Published 13 Jun 2025
Updated 13 Oct 2025
8 min read
Receiving an automated response from Microsoft's SNDS (Smart Network Data Services) IP review process can be perplexing, especially when you are trying to resolve an urgent email deliverability issue. Many email senders encounter this auto-reply after submitting a request to delist an IP address that has gone red in SNDS, often due to bounce management errors or other reputation issues. This initial message, which often states it's from an unattended mailbox, can leave you wondering about the next steps and whether your submission has been effectively received.
This experience is a common part of interacting with Microsoft's sender support. The auto-reply confirms your ticket has been logged and the system is aware of your IP review request. However, it does not provide an immediate resolution or direct human interaction. The key is understanding what this message signifies and how to proceed to ensure your IP address is properly reviewed and any blocklists (or blacklists) are promptly addressed, helping you to maintain optimal email deliverability.
Understanding the Microsoft SNDS auto-reply
When you submit an IP review request to Microsoft's Sender Support, the first email you typically receive is an automated acknowledgment. This email serves as a confirmation that your submission has been successfully received by their ticketing system. It will usually contain your ticket number in the subject line and list the IP address you submitted for review. Crucially, it will often include a disclaimer stating, "Please do not reply to this message as it is from an unattended mailbox. Any replies to this email will not be responded to or forwarded. This service is used for outgoing emails only and cannot respond to inquiries."
This message can be confusing because it confirms receipt but simultaneously tells you not to reply, which might feel like a dead end. However, it's essential to understand that this is standard procedure. It means your request is in the queue, and a human will review it. You can find more details about the process on the official SNDS FAQ page.
The auto-reply, despite its stern warning, is a positive sign. It indicates that your attempt to engage with Microsoft's support system was successful at the first hurdle. The critical next step is to wait for a subsequent, human-generated response, which will address the specifics of your IP block or blacklist status. Ignoring the auto-reply's instruction and attempting to reply will not speed up the process and might even complicate it.
Example auto-reply from Microsoft
Microsoft SNDS Auto-Replytext
Dear XXX,
Please note that your ticket number is in the subject line of this mail.
AAA.BBB.CCC.DDD (IP address)
Note: Errors are unlikely, however, if an error is indicated, please resubmit the specific IP or IP range.
Thank you,
Outlook.com Deliverability Support
Please do not reply to this message as it is from an unattended mailbox. Any replies to this email will not be responded to or forwarded. This service is used for outgoing emails only and cannot respond to inquiries.
This message confirms receipt but requires you to await a human response. Do not reply to this email.
When and how to expect a human response
After the initial auto-reply, the typical waiting period for a human-generated response from Microsoft is generally within 24 to 48 hours. This follow-up email will usually provide a more specific assessment of your IP status and, if applicable, confirm that the block has been mitigated or provide further instructions.
However, sometimes these responses can be delayed, or in rare cases, you might not receive a human follow-up at all. If 48 hours pass without a further message, it's generally advisable to resubmit your IP review request. Be sure to keep a record of your submission dates to avoid creating multiple, overlapping tickets for the same issue. For insights into common issues, you can review Microsoft SNDS common errors.
When the human response does arrive, that is the email you should, and likely will need to, reply to if further clarification or persistent issues require it. Unlike the automated message, this email is monitored by a support agent. For more general strategies on dealing with Microsoft's automated responses and email blocking, consider exploring how email marketers handle Microsoft Sender Support.
Initial auto-reply
Purpose: Acknowledges receipt of your IP review request.
Content: Provides ticket number and IP, warns against replies.
Action: Wait patiently for a human follow-up.
Human response
Purpose: Provides specific assessment and potential resolution.
Timing: Usually within 24-48 hours.
Action: This is the email to engage with for further discussion.
Proactive steps to prevent future blocklists
While awaiting a response from Microsoft, it is crucial to implement proactive measures to prevent future blocklists (or blacklists). One of the most common reasons for IP blocks is poor bounce management. An IP can go red in SNDS due to errors managing bounces, which signals to mailbox providers that you might be sending to invalid addresses or not cleaning your lists effectively. Addressing these issues at the source is vital for long-term deliverability.
Additionally, robust email authentication using DMARC, SPF, and DKIM is paramount. These protocols help verify your identity as a sender and protect your domain from spoofing. Consistent monitoring of your DMARC reports can provide invaluable insights into email authentication failures, allowing you to identify and rectify issues before they impact your sender reputation and lead to IP blocks. This is especially relevant for understanding what causes Microsoft S3150 blocklist bounces and how to resolve them.
Implementing a strong DMARC policy, along with proper SPF and DKIM setup, ensures that your legitimate emails are less likely to be flagged as spam. Regular review of your sending practices and compliance with major mailbox provider guidelines, such as those from Google and Yahoo, will significantly reduce the risk of future IP blockages.
Monitor SNDS regularly: Keep an eye on your IP status and reputation to catch issues early.
Implement DMARC, SPF, and DKIM: Strengthen your email authentication to build sender trust.
Segment your sending: Separate transactional emails from marketing emails to protect critical streams.
Monitoring and advanced troubleshooting
Effective monitoring is a continuous process that goes beyond merely reacting to blocklists. Regularly checking your SNDS data for any changes in your IP status, even if it's currently showing as normal, is crucial. Sometimes, issues can resolve themselves without explicit notification from Microsoft. If you notice a block has lifted, but haven't received a human response, it might be best to observe the situation rather than poking the bear, as one marketer put it. For comprehensive guidance on monitoring, consult our guide on troubleshooting Microsoft email deliverability issues.
Beyond SNDS, other indicators can reveal underlying deliverability problems. Low inbox placement rates, increased bounce rates from Microsoft domains, or even recipient complaints can point to issues even when SNDS appears clean. If you are operating in a shared IP environment, the actions of other senders on the same IP can also affect your reputation. Consistent blocklist monitoring with tools like Suped can provide an extra layer of protection, alerting you to any listing on major blocklists (or blacklists) that might impact your email deliverability to Microsoft.
Status
Meaning
Action required
Green
Good standing, low complaint rate.
Maintain good sending practices.
Yellow
Moderate standing, increased complaint rate.
Investigate sending practices, consider list hygiene.
Red
Poor standing, high complaint rate or spam activity.
Immediate investigation and IP review request needed.
Restoring your sender reputation
Dealing with Microsoft's SNDS IP review process can be a waiting game, but understanding the steps and anticipating the responses is key to effective deliverability management. The initial auto-reply is simply a confirmation, not a resolution. Patience and persistence are necessary while awaiting a human response, which typically arrives within 24-48 hours. During this period, and continuously, focus on robust sending practices, meticulous bounce management, and strong email authentication.
By actively monitoring your IP reputation, not just on SNDS but through other deliverability metrics, you can proactively prevent issues or address them swiftly. Tools like Suped's DMARC monitoring provide comprehensive visibility into your email ecosystem, helping you maintain a healthy sender reputation and ensure your legitimate emails reach the inbox.
Views from the trenches
Best practices
Regularly monitor SNDS for IP health and proactively address any degradation to maintain email deliverability.
Ensure proper bounce management is in place to prevent IP reputation issues with major mailbox providers like Microsoft.
Utilize DMARC reporting tools like Suped to gain comprehensive visibility into email authentication and delivery.
When submitting IP review requests, provide clear, concise details about the issue and the steps taken to remediate it.
Common pitfalls
Expecting an immediate resolution or a detailed technical explanation from Microsoft's initial automated replies.
Repeatedly resubmitting the same IP review request without waiting for the initial human response can cause delays.
Not addressing underlying email sending hygiene issues, which can lead to recurring blocklists.
Ignoring the "unattended mailbox" warning and replying to automated messages, which will not be seen.
Expert tips
If no human response is received within 48 hours, consider resubmitting your request, but track submissions carefully.
Keep detailed records of all communication and actions taken for any IP blocklist incidents.
Implement robust email authentication (SPF, DKIM, DMARC) to strengthen your sender reputation.
Investigate any sudden drops in email deliverability even if SNDS shows a 'normal' status, as other factors may be at play.
Marketer view
Marketer from Email Geeks says: I often receive these auto-responses when submitting IP review requests, indicating that the submission has been logged successfully.
2023-01-01 - Email Geeks
Marketer view
Marketer from Email Geeks says: The actual human response typically follows within 24 to 48 hours after the initial auto-reply is received.
This message confirms receipt but requires you to await a human response. Do not reply to this email.
