What is Microsoft SNDS (Smart Network Data Services)?
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If a chunk of your list uses Outlook, Hotmail, or Live addresses, you need to know how Microsoft sees your sending reputation. That's exactly what Microsoft SNDS (Smart Network Data Services) is for.
SNDS is Microsoft's free reporting portal for email senders. You connect it to the IP addresses you send from, and it shows you what Microsoft's filters are seeing on their end. Think of it as a window into how Hotmail and Outlook are judging your mail before it ever reaches the inbox.
The main things SNDS surfaces for each of your IPs are your reputation status, complaint rates, and spam trap hits. Each IP gets a color-coded status: green means you're in good shape, yellow is a warning, and red means Microsoft is actively filtering or blocking your mail.
Complaint data in SNDS comes from users who hit "mark as junk" on your messages inside Outlook and Hotmail. If you're seeing elevated complaint rates, that's a signal your list has people who didn't ask to hear from you, or who've simply forgotten they signed up.
Spam trap hits are the one you really don't want to ignore. A hit means mail from your IP reached an address Microsoft controls specifically to catch low-quality senders. That almost always points to a list hygiene problem.
SNDS is free to use, but you do need to verify ownership of each IP before the data unlocks. If your ESP sends on shared IPs, you may not have direct access, so it's worth asking your provider whether they monitor SNDS on your behalf.
Ready to sign up? Check out how to get access to SNDS and what each data point actually means once you're in. If your reputation is already in the red zone and you're not sure why, our SOS hotline is free and we'll help you dig in.
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