# Why is my email going to spam in Outlook but not Gmail?

> Mail lands in Outlook spam but not Gmail because Microsoft weighs IP reputation and its own authentication rules differently. Here's how to diagnose and fix it.

Your mail lands in Outlook's Junk folder but Gmail's inbox because Microsoft and Google score senders differently: Microsoft leans heavily on your sending **IP reputation** and on its own consumer authentication rules, while Google weights **domain reputation** and engagement. The same message can pass Gmail's checks and still trip Outlook's if your IP is unknown or lightly complained-about, or if you send high volume to Outlook.com without full SPF, DKIM, and DMARC. Start by confirming all three authentication checks pass and align, then check your IP reputation in Microsoft's free SNDS tool.

## Quick Takeaways

- Outlook filtering is **IP-reputation-first**; Gmail is **domain-reputation-first** — so a clean domain with a cold or shared IP can inbox at Gmail and junk at Outlook.
- Since **May 5, 2025**, Microsoft routes high-volume mail (5,000+/day to Outlook.com, Hotmail, Live, MSN) to Junk unless it has SPF, DKIM, **and** DMARC, per [Microsoft's sender requirements](https://techcommunity.microsoft.com/blog/microsoftdefenderforoffice365blog/strengthening-email-ecosystem-outlook%E2%80%99s-new-requirements-for-high%E2%80%90volume-senders/4399730).
- The hard-reject version of that rule returns `550 5.7.515 Access denied, sending domain … does not meet the required authentication level`.
- Check your IP reputation at Microsoft's free [Smart Network Data Services (SNDS)](https://sendersupport.olc.protection.outlook.com/snds/index) and enroll in the Junk Email Reporting Program (JMRP) to see complaints.
- Gmail passing does **not** mean you are authenticated correctly for Outlook — verify SPF, DKIM, and DMARC all pass and align with your From domain.
- Content and links that Gmail tolerates can still raise Outlook's spam score; Outlook is more sensitive to spammy formatting and low text-to-image ratios.

## Why does Outlook junk mail that Gmail delivers?

Because the two providers optimize for different signals. Microsoft's consumer filters (Outlook.com, Hotmail, Live, MSN) put a lot of weight on the reputation of the **IP address** you send from, tracked per IP through its [SNDS](https://sendersupport.olc.protection.outlook.com/snds/index) program. Google's filters put more weight on **domain reputation** and recipient engagement — opens, replies, and "not spam" actions build a domain's standing over time.

That difference explains the split you are seeing. If you send from a new, shared, or lightly-warmed IP, Gmail may still inbox you on the strength of your domain history and engagement, while Outlook — seeing an IP it does not trust — drops you in Junk. It also cuts the other way: a brand-new domain on a well-established IP can inbox at Outlook and struggle at Gmail. Neither provider is "wrong"; they are asking different questions about the same message.

Authentication is the common denominator. Both require [email authentication](/learning/what-is-email-authentication-and-why-does-it-matter), but Microsoft made its consumer rules explicit and enforced them in 2025, so a gap that Gmail quietly tolerates can become a hard filter at Outlook.

## What signal maps to what fix?

Read the symptom, then act. This table covers the common Outlook-but-not-Gmail patterns:

| Signal you see | What it means | First action |
|---|---|---|
| Inbox at Gmail, Junk at Outlook, all auth passes | IP reputation or Outlook-specific filtering, not authentication | Check the sending IP in [SNDS](https://sendersupport.olc.protection.outlook.com/snds/index); warm the IP if new |
| `550 5.7.515 … does not meet the required authentication level` | High-volume mail without full SPF + DKIM + DMARC | Publish all three and confirm DMARC alignment |
| Junk at Outlook only after volume increased | Crossed Microsoft's 5,000/day high-volume threshold | Ensure DMARC is present and passing before scaling |
| `5.7.1` / blocked at Outlook | IP on a Microsoft block or poor SNDS reputation | Review SNDS status; submit sender support / mitigation |
| Gmail fine, Outlook flags content | Spammy formatting, image-heavy, risky links | Fix text-to-image ratio and link hygiene |

## Is my email properly authenticated for Outlook?

Confirm that SPF, DKIM, and DMARC all pass **and align** with your From domain — passing Gmail is not proof you have. Since May 5, 2025, [Microsoft requires](https://techcommunity.microsoft.com/blog/microsoftdefenderforoffice365blog/strengthening-email-ecosystem-outlook%E2%80%99s-new-requirements-for-high%E2%80%90volume-senders/4399730) any sender pushing 5,000 or more messages a day to its consumer domains to publish SPF and DKIM that pass, and a DMARC record of at least `p=none` that aligns with SPF or DKIM. Non-compliant high-volume mail is filtered to Junk; the enforced form returns `550 5.7.515 Access denied, sending domain [yourdomain] does not meet the required authentication level`, documented on [Microsoft's 550 5.7.515 support page](https://support.microsoft.com/en-us/outlook/fix-ndr-error-550-5-7-515-in-outlook-com).

Work through it in order:

1. **Publish SPF** listing every server that sends for your domain, and verify it with the [SPF checker](/tools/spf). Keep it under the 10-DNS-lookup limit.
2. **Enable DKIM** in your sending platform and publish the public key; confirm the signature validates with the [DKIM checker](/tools/dkim).
3. **Publish DMARC** at `_dmarc.yourdomain.com` starting at `v=DMARC1; p=none; rua=mailto:reports@yourdomain.com`, and check it with the [DMARC checker](/tools/dmarc).
4. **Confirm alignment** — the domain that passes SPF or DKIM must match your visible From domain. This is the step people miss, and it is exactly the failure behind [Microsoft 365's 550 5.7.x access-denied bounces](/learning/fix-microsoft-365-550-5-7-x-access-denied) too.

Read the message headers to verify: open the `Authentication-Results` header on a message that landed in Outlook Junk and check that `spf=pass`, `dkim=pass`, and `dmarc=pass` all reference your domain.

## How do I check and fix my IP reputation at Outlook?

Use Microsoft's free tools, because Outlook's decision is driven by data you can actually see. [Smart Network Data Services (SNDS)](https://sendersupport.olc.protection.outlook.com/snds/index) shows how Microsoft rates each of your sending IPs — traffic volume, spam-trap hits, and complaint rate. If SNDS flags an IP as red or shows a high complaint rate, that is almost certainly why Outlook junks you while Gmail does not.

Two Microsoft programs do the heavy lifting:

- **SNDS** — request access for your sending IP ranges and monitor the reputation and complaint data Microsoft records per IP. It is IP-centric, so it is most useful when you control a dedicated IP.
- **JMRP (Junk Email Reporting Program)** — a complaint feedback loop that forwards copies of messages Outlook users mark as junk, so you can suppress those recipients. Enroll and start removing complainers.

If you send from a **shared IP** (most people on an ESP do), you inherit the reputation of everyone else on it, and you cannot fix that pool directly — your levers are cleaning your own list and, if the pool is bad, asking your provider to move you or moving to a dedicated IP you can warm. If you moved to a new IP recently, warm it: ramp volume gradually over days to weeks so Microsoft builds trust before you send at full scale.

## Why does volume change Outlook's behavior but not Gmail's?

Because Microsoft's explicit consumer rules trigger at a volume threshold. Below roughly 5,000 messages a day to Outlook.com addresses you may skate by on a partial setup; cross it and Microsoft's [high-volume requirements](https://techcommunity.microsoft.com/blog/microsoftdefenderforoffice365blog/strengthening-email-ecosystem-outlook%E2%80%99s-new-requirements-for-high%E2%80%90volume-senders/4399730) apply, and a missing or misaligned DMARC record that never mattered before suddenly sends everything to Junk. This is the classic "it worked until we grew" report — nothing about your content changed, you simply tripped a rule that scales with volume.

The fix is to get fully compliant *before* you scale: SPF, DKIM, and a passing, aligned DMARC record in place while you are still small, so growth never flips a switch. If your overall picture is broader than one provider, our guide on [why emails land in spam and how to fix it](/learning/why-am-i-not-receiving-emails-how-to-troubleshoot) covers the wider triage.

## Common issues with Outlook spam filtering

### Everything passes authentication but Outlook still junks me

This is the signature of an IP-reputation problem. Check the sending IP in SNDS — a poor score or high complaint rate will junk you at Outlook while Gmail, weighting your domain history, still delivers. Clean your list, enroll in JMRP to shed complainers, and warm the IP if it is new.

### Only Outlook.com/Hotmail addresses are affected, not corporate Microsoft 365

Consumer Outlook.com and hosted Microsoft 365 tenants apply filtering differently. If corporate 365 recipients are the ones blocking you, you are more likely hitting a tenant-level rule or the `550 5.7.x` access-denied path — see [fixing Microsoft 365 550 5.7.x access denied](/learning/fix-microsoft-365-550-5-7-x-access-denied). Consumer-only junking points back at IP reputation and the high-volume rules.

### My content is fine but Outlook flags it anyway

Outlook is stricter than Gmail on formatting. A high image-to-text ratio, link shorteners, mismatched or bare display links, and "spammy" phrasing raise its score faster than Gmail's. Send a plain, balanced message as a control; if that inboxes and your campaign does not, the content is contributing.

### It started right after we increased send volume

You almost certainly crossed Microsoft's 5,000/day high-volume threshold. Confirm SPF, DKIM, and DMARC all pass and align, because that rule now applies to you even though it did not at lower volume.

## Frequently asked questions

### Does passing Gmail mean I will pass Outlook?

No. Gmail and Outlook weight signals differently — Gmail leans on domain reputation and engagement, Outlook on IP reputation and its consumer authentication rules. Verify Outlook specifically by sending a test to an Outlook.com address and reading the `Authentication-Results` header.

### Do I need a dedicated IP to inbox at Outlook?

Not necessarily. Plenty of senders inbox from well-managed shared pools. A dedicated IP helps when you send enough volume to build your own reputation and want to control it, but it must be warmed — a cold dedicated IP is worse than a good shared one.

### What is the fastest way to see why Outlook junks me?

Request SNDS access for your sending IP and read the reputation and complaint data. Combined with the `Authentication-Results` header on a junked message, that tells you within minutes whether the problem is IP reputation or authentication.

### Will a stricter DMARC policy help delivery at Outlook?

Having a passing, aligned DMARC record is what matters for Microsoft's high-volume rule; moving from `p=none` to `p=reject` mainly protects you from spoofing rather than boosting inbox placement. Fix alignment and IP reputation first — those move Outlook placement, policy strength does not.

Palisade automates the authentication side of this for every domain you manage: it publishes correct, aligned SPF, DKIM, and DMARC records, reads your DMARC aggregate reports to surface unauthenticated or unaligned senders before they cost you delivery, and flags when a new sending source could break placement at Outlook or Gmail. Run your domain through the free [Email Security Score](/tools/email-security-score) tool to see exactly which of Microsoft's requirements you meet today.

## Related reading

- [Why is Yahoo blocking my emails as unauthenticated?](/learning/why-is-yahoo-blocking-my-emails-as-unauthenticated)
- [Why is Gmail rejecting my emails with a 550 error?](/learning/why-is-gmail-rejecting-emails-550-error-2026)
- [Why am I not receiving emails? How to troubleshoot](/learning/why-am-i-not-receiving-emails-how-to-troubleshoot)