What does Microsoft SNDS show?

SNDS shows per-IP data: message volume, complaint rate (%), spam trap hits, filter results (what percentage of your email Microsoft filtered), and your IP's status color (green=good, yellow=warning, red=blocked). Data is IP-specific, not domain-specific.

How do I register for SNDS?

Go to sendersupport.olc.protection.outlook.com/snds → Sign in with a Microsoft account → Request access → Enter your sending IP addresses. Microsoft verifies you control the IPs (usually via whois or email to the IP's registered contact). Approval takes 24-48 hours.

My SNDS shows red status. What do I do?

Red means Microsoft is blocking or severely filtering your IP. Check: complaint rate (must be under 0.3%), spam trap hits (should be zero), and volume patterns (sudden spikes trigger filtering). Fix the underlying issue, then submit a delisting request through Microsoft's sender support portal.

Is SNDS enough or do I also need Google Postmaster Tools?

You need both. SNDS covers Outlook.com/Hotmail/Live.com (~15-20% of recipients). Google Postmaster Tools covers Gmail (~30-40% of recipients). Together they cover the majority of your recipient base. Neither alone gives the full picture.

Does SNDS show domain reputation?

No. SNDS is IP-based only. It shows reputation for specific sending IPs. For domain-level reputation, use Google Postmaster Tools (which shows domain reputation for Gmail). Microsoft evaluates both IP and domain but only exposes IP data through SNDS.

Microsoft SNDS: Complete Setup and Interpretation Guide

Why SNDS Matters

Google Postmaster Tools gets all the attention, but Outlook.com (including Hotmail and Live.com) represents 15-20% of most email audiences. SNDS is the only way to see how Microsoft evaluates your sending.

If your Gmail deliverability is fine but Outlook is filtering you, SNDS tells you why.

Setup

Step 1: Register

Go to sendersupport.olc.protection.outlook.com/snds
Sign in with a Microsoft account
Click "Request Access"
Enter your sending IP addresses (find these in your ESP dashboard or server config)
Microsoft verifies you control the IPs — approval takes 24-48 hours

Step 2: Access Data

Once approved, the SNDS dashboard shows daily data per IP:

Metric	What It Shows
Activity period	Date range of data
Message volume	Number of messages from this IP to Microsoft
Complaint rate	% of recipients who reported your email as spam
Trap hits	Number of messages sent to Microsoft's spam traps
Filter results	What % of your email Microsoft's filters flagged
Status	Green (good), Yellow (warning), Red (blocked)

Step 3: Interpret

Green status: Your IP is in good standing. Microsoft delivers most of your email to the inbox. Maintain current practices.

Yellow status: Warning. Your complaint rate or trap hit count is elevated. Investigate immediately:

Check recent campaigns for high complaints
Review list hygiene (remove unengaged contacts)
Verify authentication

Red status: Your IP is blocked or severely filtered. Microsoft is spam-filtering most of your email.

Check complaint rate (must be under 0.3%)
Check for spam trap hits (should be zero)
Fix the cause
Submit delisting request via Microsoft's support portal

SNDS vs Google Postmaster Tools

Feature	SNDS	Google Postmaster Tools
Provider	Outlook.com/Hotmail/Live	Gmail
Data basis	IP-based	Domain-based + IP-based
Domain reputation	No	Yes (High/Medium/Low/Bad)
IP reputation	Yes (color-coded)	Yes (High/Medium/Low/Bad)
Spam rate	Yes (complaint %)	Yes (complaint %)
Authentication	No	Yes (SPF/DKIM/DMARC pass rates)
Trap hits	Yes	No (not exposed)
Encryption	No	Yes (TLS %)
Delivery errors	No	Yes
Access	IP registration required	Domain verification required

Use both. Together they cover 50-60% of your recipient base with concrete data.

Responding to SNDS Issues

High Complaint Rate

Microsoft's threshold: above 0.3% is problematic.

Identify which campaigns generated complaints (check campaign timing vs SNDS data dates)
Review the audience segment — were you sending to unengaged contacts?
Implement engagement-based segmentation
Reduce sending to Outlook recipients until complaint rate drops

Spam Trap Hits

Any trap hit is concerning.

Your list contains recycled email addresses (previously real, now traps)
Clean your list: remove all contacts with no engagement in 180+ days
Validate your list through ZeroBounce or NeverBounce
Implement sunset policy to prevent future trap accumulation

Red Status (Blocked)

Fix complaint and trap issues first
Go to sender.office.com or SNDS support portal
Submit delisting/unblock request
Include: what caused the issue, what you've fixed, and your sending practices going forward
Wait for Microsoft review (can take 24-72 hours)

Microsoft's May 2025 Bulk Sender Requirements

Microsoft joined Gmail and Yahoo in requiring authentication for bulk senders to Outlook.com:

SPF must pass
DKIM must pass
DMARC must be published (minimum p=none)
Compliant unsubscribe mechanism
Valid sender address

Non-compliant email is junked initially, rejected eventually.

Practitioner note: SNDS is the forgotten monitoring tool. Every client I onboard has Google Postmaster Tools set up. Maybe 10% have SNDS. When Outlook deliverability is poor, the first question is "do you have SNDS?" and the answer is almost always no. If you send to any Outlook/Hotmail/Live.com addresses, register for SNDS today.

Practitioner note: SNDS is IP-based, not domain-based. If you're on shared IPs, the SNDS data reflects the entire shared pool — not just your sending. This is another argument for dedicated IPs at scale: you can see and control your own SNDS data.

If you need Outlook deliverability diagnosed and fixed, schedule a consultation — I use SNDS alongside Postmaster Tools for complete deliverability visibility.

Sources

Microsoft: SNDS
Microsoft: Sender Support
Microsoft: Outlook Sender Requirements

v1.0 · March 2026