Microsoft SNDS: How to Monitor Your Sending Reputation at Outlook

Microsoft SNDS (Smart Network Data Services) is a free Microsoft service that reports how Microsoft's consumer mail systems see the IP addresses you send from. It gives you per-IP traffic volume, complaint rate and a colour-coded reputation status for Outlook.com, Hotmail and Live recipients. It is monitoring, not remediation: registering an IP does not improve your reputation by itself, but it tells you whether you have a problem and whether your fixes are working.

If your placement at Outlook.com has slipped and you have no visibility into why, SNDS is the closest thing to a native reputation view you can get. This guide covers what it does and does not cover, how to register your IPs, how to read the dashboard, and how to verify the data is flowing.

What SNDS actually gives you (and what it doesn't)

SNDS reports on IP addresses, not domains. If you send from a dedicated IP, you can register it and see Microsoft's view of that address. If you send through a shared pool, the data belongs to the pool operator, not to you, and there is little you can act on.

Scope matters here. SNDS covers Microsoft's consumer mail properties — Outlook.com, Hotmail and Live. It does not cover Exchange Online or Microsoft 365 business tenants, which have their own filtering and reporting. A clean SNDS record says nothing about how a corporate Microsoft 365 mailbox treats your mail.

The data is aggregated daily, so expect a lag of roughly a day rather than real-time numbers. And a green status is not a guarantee of inbox placement. It means Microsoft's systems are not currently flagging your IP for volume or complaint problems. Content, engagement, authentication and recipient behaviour still decide the inbox.

For a wider view of the market, our ranking of the Best Email Marketing Platforms shows what each service really costs for your number of contacts.

Before you start: what you need

• The static sending IPs you actually send from. Not your provider's shared pool. If you are on a shared IP, SNDS is largely not actionable for you — rely on your provider's reputation tooling instead and skip the rest of this section.
• A Microsoft account to sign in with.
• A monitored mailbox that can receive the verification email and later status-change notifications.
• Access to DNS if you choose the TXT verification route, or the ability to ask whoever manages the reverse-DNS/WHOIS contact domain.

If you send from a /24, you register each address individually or use the range tools Microsoft provides in the interface. There is no bulk "add my whole subnet and forget it" shortcut that skips verification.

Registering your IPs in SNDS, step by step

The interface is plain and mostly text-based. Here is the sequence, with the exact fields you will fill in.

1. Sign in. Go to the SNDS sign-in page and authenticate with your Microsoft account. You will land on a dashboard that lists any IPs already associated with your account — empty on first use.

2. Start a new request. Choose the option to request new data or add an IP. This opens a short form.

3. Enter the IP address. Type the dotted-quad address exactly as you send from — for example 203.0.113.45. Do not enter a CIDR range like 203.0.113.0/24 in the single-IP field; if you need a range, use the range option Microsoft provides separately.

4. Provide a contact email. Use an address that a human actually reads. Microsoft sends verification messages and, later, notifications when status changes. An unmonitored alias is an easy way to miss a reputation drop.

5. Choose a verification method. Email verification sends a link to the contact address. DNS TXT verification asks you to add a TXT record Microsoft generates at the domain associated with the IP's reverse DNS or WHOIS contact. DNS is the more durable option if the contact mailbox may change.

6. Submit and wait. Email verification typically arrives quickly; DNS verification depends on your TTL. Verification overall can take up to a day.

7. Confirm the IP appears in your dashboard list. Until verification completes, the IP shows no data. Once it is verified, the row populates with status, volume and complaint figures.

The dashboard itself is a table: one row per IP, with columns for the address, its status, the data Microsoft has collected, and the complaint rate. There is no charting to speak of — you are reading numbers and colours.

Reading the dashboard: status colours, complaint rate and volume

Three things matter per IP.

Status. Green means normal, yellow means mixed, red means Microsoft is filtering or blocking a portion of your mail, and grey or unknown means there is not enough data yet. Red is the signal to act; grey usually just means the IP is new to SNDS or sending too little volume to assess.

Complaint rate. This is the proportion of recipients who marked your mail as junk, shown as a percentage. It is the fastest-moving signal on the page and the one most within your control. Many senders treat a complaint rate creeping toward 0.1% as a warning sign, but check Microsoft's current published guidance rather than treating any single number as a hard threshold — the trend matters more than one day's reading.

Volume and filtering breakdown. SNDS shows how much mail you sent and how much was filtered or blocked. A volume spike combined with a rising complaint rate is one pattern that can push an IP toward red.

Treat the complaint column as your early-warning system and the status colour as the summary.

A worked example: from red to green on one IP

This is an illustrative scenario, not a customer story.

A sender runs a weekly newsletter from one dedicated IP. The list grew partly through a co-registration partner. SNDS shows the IP as red, with a complaint rate of a few tenths of a percent (invented for illustration), and a large share of mail going to the junk folder.

The diagnosis: the co-registered segment complains at a high rate, and that source never had confirmed opt-in. The fixes are straightforward but slow:

• Suppress everyone who has complained, and keep them suppressed.
• Remove the co-registration source entirely.
• Add double opt-in for all new signups.
• Reduce send volume for two weeks rather than pushing the same list harder.
• Check SNDS daily and log the numbers.

Week by week, the dashboard moves red to yellow to green as complaints fall and volume stays modest. Recovery is slow and depends on sustained low complaints; in this illustrative example, a single bad send undoes the progress made over the preceding weeks. The lesson is that SNDS told the sender what was wrong; the list hygiene did the fixing.

How to verify it's working

Four checks confirm the setup is live and the data is trustworthy.

1. The IP appears with a status other than "no data." If it still shows no data after a day, recheck verification.
2. Send a small test campaign to Outlook.com or Hotmail addresses you control, then confirm the SNDS volume counter increments within a day.
3. Confirm the contact email receives Microsoft's notification emails when status changes. If it does not, your alerts are going nowhere.
4. Cross-check SNDS complaint numbers against your own feedback loop and your ESP's complaint rate. They should move in the same direction. If SNDS shows complaints and your provider shows none, investigate your feedback loop setup.

Common mistakes and fixes

• Registering a shared ESP IP you do not control. No action is possible on your side — talk to your provider about their reputation tooling instead.
• Entering a CIDR range in the single-IP field. Use the single-IP field for single IPs and the range option for ranges.
• Using an unmonitored contact address. You will miss status-change alerts. Use a mailbox someone reads.
• Assuming green means inbox. It does not. Authentication, content and engagement still decide placement.
• Ignoring the complaint column because the status is green. Complaints rise before status turns. Watch the trend.
• Forgetting to register new sending IPs. Add them the day you start sending from them.
• Treating SNDS as a fix rather than a monitor. It shows the problem; list hygiene and authentication solve it.

Where SNDS fits in a broader reputation routine

SNDS covers Microsoft consumer mail. Google Postmaster Tools covers Gmail. Neither covers everything, so run both alongside your ESP's own reputation tooling and check them on a fixed weekly cadence. Keep a simple log — date, IP, status, complaint rate, action taken — so you can see whether a change actually helped.

SNDS assumes your authentication and suppression are already in order. That is the part Mailerflow's deliverability setup handles: own-domain sending with guided DKIM, SPF and DMARC setup and automatic verification, plus automatic suppression of bounces and complaints, reputation monitoring and warm-up limits. If you are still assembling that foundation, it is worth getting right before you spend time interpreting SNDS numbers.

FAQ

Is SNDS free? Yes. Microsoft provides SNDS at no cost to senders who can verify control of the IP addresses they register.

Does SNDS cover Microsoft 365 or Exchange Online business mail? No. SNDS covers Microsoft consumer mail — Outlook.com, Hotmail and Live. Business tenants have separate filtering and reporting.

Can I register a shared IP? You can register an IP you do not exclusively control, but the data will reflect the whole pool's behaviour and you will not be able to act on it meaningfully. Talk to your provider instead.

How long until data appears? Verification can take up to a day, and data is aggregated daily. Expect a lag of roughly a day after you start sending.

Does a green status mean my mail lands in the inbox? No. Green means Microsoft is not currently flagging your IP for volume or complaint problems. Placement still depends on authentication, content and engagement.

What complaint rate should I worry about? Check Microsoft's current published guidance rather than fixing on one number. A rising trend is the signal to act, even below any published threshold.

How do I remove an IP I no longer send from? Use the removal option in your SNDS dashboard for that IP. Removing it stops the data collection and the associated notifications.

If your Outlook.com placement has slipped, the fastest path is to confirm your authentication is solid, then register your sending IPs in SNDS and watch the complaint column. Set up your sending domain in Mailerflow with guided DKIM, SPF and DMARC and automatic verification, so the reputation data you collect reflects list quality rather than a missing DNS record.