Where you saw it: Throttling or junk filing at Microsoft domains with no visible cause, or a deliverability audit asking for SNDS data you do not have.
Why it happens
- Not enrolled, which is the default state.
- Sending from a shared platform IP you do not control, which makes you ineligible.
- Enrollment request sent to an address on the IP's WHOIS record that nobody monitors.
- Volume below Microsoft's reporting threshold, leaving the data sparse.
The fix, in order
Confirm you can prove control of the IP
Enrollment verifies against the WHOIS contact or a designated address for the range. On a shared platform IP you cannot, and your provider holds this data instead.
Request access for your ranges
Submit the IP ranges through the SNDS site. Approval goes to an address associated with the range, so check that it is monitored before you start.
Read the complaint rate column first
It is the number Microsoft acts on. Yellow or red status against an IP explains throttling and junk filing more reliably than any content analysis.
Read the complaint rate and the filter result together
Trap hit counts left the SNDS data report on July 22, 2026, so stop looking for that column. What remains is the complaint rate and the green, yellow or red filter result per IP. A rising complaint rate on a list segment is now your earliest sign that it holds people who never opted in.
Join the Junk Mail Reporting Program too
SNDS gives you aggregates. The reporting program forwards individual complaints so you can suppress those people.
How to know it worked
The short version
- Your IP ranges appear in the SNDS dashboard with data.
- Status reads green with a complaint rate below 0.3%.
- The filter result holds at green across a full week of normal sending, not only on a quiet day.
Where the approval email goes
Microsoft has moved SNDS to a new portal, at substrate.office.com/ip-domain-management-snds, which replaces the sendersupport.olc.protection.outlook.com site most setup guides still link to.
You sign in with a Microsoft account and request an IP, a range or an ASN. Its FAQ explains who may approve the request. The portal looks up reverse DNS for the IPs, and where the hostnames share a domain it offers postmaster@ and abuse@ at that domain. It also reads contact addresses from the RDAP allocation record, and for an ASN it uses the email addresses found in the ASN record.
Say your sending IPs reverse-resolve to mta1.yourcompany.com and mta2.yourcompany.com. Before you submit, mail postmaster@yourcompany.com and abuse@yourcompany.com and see who receives it. If neither mailbox exists, create them first, or the approval link goes nowhere.
Reading one day of data
Each row covers one IP for one period and shows RCPT commands, DATA commands, message recipients, a filter result and a complaint rate. The filter result is a color with a published meaning: green is under 10% of mail judged spam, yellow is between 10% and 90%, and red is over 90%.
Complaint rate is complaints divided by message recipients for the period. Data is aggregated once a day at about midnight Pacific time and kept for 90 days, and an IP that sent fewer than 100 messages that day may show nothing. A blank row on a quiet day means nothing was measured.
Compare RCPT commands with message recipients. Microsoft's FAQ calls a gap of a few percent normal and says a large one can point to out of date recipient lists. If you issued 12,000 RCPT commands and only 10,300 recipients made it onto messages, about 1,700 addresses (14%) were refused during the SMTP conversation. That gap is the part list verification can narrow.
One dated change: the portal's notice says trap hit counts are no longer included in the data report from July 22, 2026. Older guides tell you to watch a column you may no longer see.
Questions people ask
What is the difference between SNDS and the Junk Mail Reporting Program?
SNDS shows aggregate reputation data for IPs you own. The reporting program forwards individual complaints as a feedback loop. Different things, both free, and both worth having.
Can I use SNDS on a shared IP?
No. Enrollment requires proving control of the address range, which on a shared platform belongs to the platform.
Does SNDS cover Microsoft 365 business tenants?
Mostly it reports on their consumer estate. Business tenant filtering is driven by per-tenant policy that no sender-side tool exposes.