What is the maximum number of IPs allowed on SNDS?

Key findings

• No official hard limit: Microsoft's public documentation for SNDS does not specify a maximum number of IP addresses allowed per account, focusing more on the data provided for registered IPs and subnetworks (e.g., /24, /19).
• Practical account limits: Industry experience suggests that a single SNDS account might have an unofficial or soft limit, often cited around 5,000 IP addresses. Beyond this, senders typically create multiple SNDS accounts to manage additional IPs.
• Subnet registration: SNDS allows registration of IP ranges (subnets) such as /24 or /19, which can cover hundreds or thousands of individual IP addresses under a single entry. This capability is key for large senders.
• System notification: If a limit is reached, the SNDS tool is generally expected to provide an explicit notification that the limit has been met, rather than silently omitting IPs.

Key considerations

• Scalability for large senders: For organizations with more than 5,000 IP addresses sending to Microsoft properties, managing multiple SNDS accounts may be necessary. This requires careful organization to ensure all IPs are monitored.
• Monitoring strategy: Even with multiple accounts, the primary goal remains to continuously monitor your IP reputation and activity. Learn more about how to get SNDS data.
• Deliverability impact: Regardless of the number of IPs, maintaining a positive sender reputation is paramount for email deliverability. Microsoft's SNDS provides critical insights for this. Mailgun's guide to Microsoft SNDS and sender reputation offers further context.
• IP warming implications: If you are managing a large volume of IPs, remember that IP warming strategies are critical for establishing good sender reputation for each IP, regardless of how many you register in SNDS.

Key opinions

• No perceived limit for some: Some marketers with high IP counts report no issues with listing thousands of IPs, especially when using subnet registrations.
• Functional limits observed: Other marketers indicate encountering a practical limit for a single SNDS account, often around 5,000 IPs.
• Tool feedback: Marketers anticipate that SNDS would explicitly inform them if they reached an IP limit, rather than silently failing to register IPs.
• Multiple accounts strategy: For very large IP portfolios, the common workaround mentioned by marketers is to set up multiple SNDS accounts.

Key considerations

• IP management overhead: Managing thousands of IPs across potentially multiple SNDS accounts increases administrative overhead. Marketers must ensure comprehensive monitoring to maintain optimal deliverability and identify any blacklist listings.
• Subnet vs. individual IP: Leveraging subnet registration is crucial for large IP volumes to simplify the process within SNDS and avoid hitting potential individual IP limits too quickly.
• Alternative monitoring: While SNDS is valuable, marketers should also consider other monitoring tools and practices to get a holistic view of their IP and domain reputation. This includes checking general IP blocklist status.
• Proactive monitoring: Marketers must proactively monitor their SNDS data to detect any issues early, as suggested in Kickbox's overview of Microsoft SNDS.

Key opinions

• Approximate limit: An expert suggests there is a practical limit to the number of IPs in one SNDS account, estimated to be around 5,000.
• Explicit notification: Experts believe that the SNDS system will clearly inform users if they have reached the maximum number of IPs for an account.
• Workaround necessity: For organizations exceeding the 5,000 IP threshold, experts confirm the need to create multiple SNDS accounts to accommodate all IP addresses.
• Subnet efficiency: Registering subnets (e.g., /24, /19) rather than individual IPs is an efficient way to manage large IP blocks within SNDS, as highlighted by experts.

Key considerations

• Account strategy: If you have a very large IP space, plan for multiple SNDS accounts from the outset. This requires a robust internal system for tracking and correlating data from different accounts.
• Data aggregation: While SNDS provides per-IP data, aggregating this data across multiple accounts for a unified view of your sending reputation can be challenging. This also applies to other tools like Gmail Postmaster Tools.
• Monitoring diligence: Even with large IP allocations, continuous and diligent monitoring of your SNDS data is crucial to quickly identify and address any issues. HighLevel's article on Microsoft SNDS emphasizes its importance.
• Troubleshooting authorization: Issues with SNDS authorization emails can occur, requiring prompt troubleshooting to ensure continued access to your IP data.

Key findings

• Subnet support: SNDS documentation outlines the ability to register entire subnets (e.g., /24, /19) rather than individual IPs, indicating support for large-scale IP management.
• Focus on data interpretation: Documentation emphasizes understanding the various data points, like complaint rates, spam trap hits, and IP status, for all registered IPs, regardless of volume.
• No explicit limits: The public documentation for SNDS does not specify a maximum number of IPs or subnets allowed per account, implying a design to accommodate a wide range of sender sizes.
• Authorization process: The documentation details the authorization process for registering IPs, which involves sending an email to a specific address within the registered IP's range to verify ownership.

Key considerations

• Operational scalability: While no hard limit is stated, large senders should consider the practical aspects of managing and interpreting data for thousands of IPs within a single interface.
• Ownership verification: Ensure proper procedures are in place for validating ownership of all IP ranges, especially when adding new or extensive blocks, to ensure successful registration in SNDS. This links to SNDS data overview.
• Impact of reputation: Microsoft's deliverability systems prioritize sender reputation over raw IP count. Regardless of the number of IPs, a poor reputation on one can affect others. See what causes deliverability degradation.
• Programmatic access: For very high IP volumes, consider if SNDS offers any API access for automated data retrieval, which would simplify managing a vast number of IPs across multiple accounts, although this is not explicitly detailed in basic user guides.