Outlook and Hotmail together represent a real share of B2B inboxes, and Microsoft's deliverability monitoring tool gets far less attention from cold email senders than its Google equivalent — mostly because it's structured differently in a way that trips people up.
Microsoft's Smart Network Data Services (SNDS) shows IP reputation and complaint rates specifically for mail delivered to Microsoft mailboxes — Outlook.com, Hotmail, and Microsoft 365 recipients. It's the closest equivalent to Gmail Postmaster Tools, but built around IP addresses as the primary unit rather than domains.
Register your sending IPs at sendersupport.olc.protection.outlook.com/snds. You'll need to verify ownership of each IP you want to monitor — this means SNDS registration has to happen per IP, which matters more than it might sound like given the next point.
SNDS tracks reputation by IP address, not by sending domain. If you're on shared IP infrastructure (see our dedicated vs shared IP guide), you may not have the access needed to register that IP yourself, since it's shared with other senders. This is one more reason dedicated IPs become worth considering at scale — direct visibility into Microsoft-specific reputation data is only available if you control the IP.
Beyond the IP-vs-domain structural difference, SNDS's interface and reporting cadence are noticeably less polished than Postmaster Tools — a real gap in tooling quality, not just a different presentation of similar data. Don't skip SNDS because it's less convenient, though: Outlook and Hotmail recipients are common enough in B2B contact lists that ignoring Microsoft-specific deliverability signals leaves a real blind spot, especially since Gmail Postmaster Tools tells you nothing about how Microsoft is treating your mail.
Smart Network Data Services, Microsoft's deliverability monitoring tool for mail sent to Outlook, Hotmail, and Microsoft 365 recipients — showing IP reputation and complaint rates, the closest equivalent to Gmail Postmaster Tools.
At sendersupport.olc.protection.outlook.com/snds, verifying ownership of each sending IP you want to monitor — registration happens per IP address, not per domain.
SNDS tracks reputation by IP address rather than domain, and on a shared IP you may not have the access needed to register and monitor it yourself, since it's shared with other senders.
For any list with a meaningful share of Outlook or Hotmail recipients, yes — Gmail Postmaster Tools tells you nothing about how Microsoft's systems are treating your mail, so skipping SNDS leaves a real blind spot in B2B cold email specifically.
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Written by
Scott Holmes
AI systems consultant based in Barrie, Ontario. Founder of Pinnacle Tech Projects. Has monitored Outlook/Hotmail deliverability through Microsoft SNDS for cold email sending infrastructure.
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