Braze inbox placement testing measures where a real campaign copy lands after Braze sends it. MailSlurp supplies controlled Gmail, Google Workspace, Outlook, and Microsoft 365 seed addresses, matches the message using a unique marker, and reports primary, tab, spam, or not-received outcomes.

This is more precise than treating a Braze spam test or content score as a delivery guarantee. Content checks can identify risky message characteristics; inbox placement records what each provider did with the message during a controlled send.

## Quick answer

To test Braze inbox placement and spam signals:

1. Create a new MailSlurp inbox placement run.
2. Copy the unique marker and all four current provider seed addresses.
3. In Braze, create or update an Internal Group configured as a **Seed Group**.
4. Add the four MailSlurp seed addresses as Braze user profiles in that group.
5. Create or clone the final Braze email campaign.
6. Put the exact MailSlurp marker in the subject or message body.
7. Use **Preview & Test** to verify the exact content and personalization.
8. Attach the Seed Group in **Target Audiences** and keep the normal campaign audience limited to controlled QA users.
9. Review the campaign summary and launch the seed test.
10. Return to MailSlurp and compare provider placement, content issues, and domain issues.

Create a fresh MailSlurp run for every campaign revision. Its marker and seed addresses identify one specific test.



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## Before you begin

Prepare the Braze email you intend to test and confirm the sending domain, sender identity, subject, preheader, links, hosted images, footer, subscription settings, and unsubscribe behavior are representative of production.

Use a dedicated name such as `MailSlurp Inbox Placement Seeds` for the Braze Seed Group. Keep the campaign's ordinary target audience restricted to an internal QA segment so the placement test cannot include customers.

## Step 1: Create a MailSlurp placement run

Open **Deliverability**, choose **Inbox placement**, and create a new test. Copy the unique marker and all four provider addresses.

![MailSlurp inbox placement setup with arrows showing the unique marker, four provider seeds, and Get your score action](/assets/guides/braze-inbox-placement-testing/01-mailslurp-seed-run.webp)

The seed set covers personal and business mailbox experiences across Gmail, Google Workspace, Outlook, and Microsoft 365. Do not reuse addresses or a marker from an earlier run.

## Step 2: Create a Braze Seed Group

In Braze, open **Settings**, select **Internal Groups**, and choose **Create internal group**. Name the group `MailSlurp Inbox Placement Seeds` and select **Seed Group** as its type. Your Braze role needs permission to view and edit Internal Groups; if those controls are not visible, ask a workspace administrator to create the group or grant the required access.

Braze's [Internal Groups documentation](https://www.braze.com/docs/user_guide/administer/global/user_management/internal_groups) explains that Seed Groups receive a copy of each email variant and can be added during campaign targeting. Braze adds `[SEED]` to the subject of seed copies, so keep the MailSlurp marker intact in the subject or body.

## Step 3: Add all current seed users

Add each MailSlurp seed by email address, external user ID, or a bulk user list. If a seed does not already exist as a Braze profile, create or import the profile first.

Confirm that the group contains exactly the four addresses supplied by the active MailSlurp run. Remove addresses from previous runs before continuing.

## Step 4: Create the marked Braze campaign

Open **Messaging** and **Campaigns**, then create an email campaign or clone the production draft. Keep the sender, message content, Liquid conditions, links, images, footer, and unsubscribe behavior identical to the version you plan to launch.

Put the exact MailSlurp marker in the subject or body. A clear subject format is:

```text
Braze Inbox Placement QA | mip-example123
```

The marker must remain visible in the message Braze sends. Check it again after any subject-line or variant edit.

## Step 5: Verify the exact campaign content

Choose **Preview & Test** and open **Test Send**. Select a representative individual user or Content Test Group, then verify the desktop, mobile, and plaintext versions before sending a content test.

![Braze Preview and Test screen with arrows showing the active placement marker, production content, and content-QA send](/assets/guides/braze-inbox-placement-testing/02-braze-campaign-test.webp)

This step checks content and personalization. The placement measurement begins when the campaign is launched with the MailSlurp Seed Group attached.

## Step 6: Attach the Seed Group in Target Audiences

Advance to **Target Audiences**. Select the controlled internal QA segment as the ordinary campaign audience, then add `MailSlurp Inbox Placement Seeds` under **Edit Seed Groups**. The control appears after an Internal Group has been configured as a Seed Group.

Review the group before launch:

- it contains the four addresses from the current MailSlurp run
- no customer addresses are present
- each email variant will be copied to the Seed Group
- the active marker is present in every variant
- the sending domain and IP pool match the campaign under review

Seed Group copies are for internal testing. Keep them separate from production suppression, engagement, and campaign reporting decisions.

## Step 7: Review and launch the test

On the Braze campaign summary, confirm the campaign name, delivery timing, controlled QA audience, Seed Group, sender, subject marker, variants, and subscription settings. Launch the campaign when each item is correct.

Braze sends seed copies in addition to the controlled audience send. Keep the MailSlurp result page open while the four provider targets arrive and are classified.

## Step 8: Read the inbox placement result

Choose **Get your score** after Braze has sent the campaign. MailSlurp updates the run as each provider copy is matched.

![Example completed MailSlurp inbox placement result with arrows showing four seed rows, provider placement, and issue tabs](/assets/guides/braze-inbox-placement-testing/03-placement-results.webp)

The example above shows the structure of a completed four-seed result: a delivery score, one row per provider, receive times, and separate content and domain issue tabs. Your placements and score will reflect the Braze sender, content, reputation, and provider classifications observed for your run.

| Result           | What it means                                                                              |
| ---------------- | ------------------------------------------------------------------------------------------ |
| Primary or inbox | The message reached the provider's main inbox experience                                   |
| Promotions       | The provider delivered the message to a promotional category rather than the primary view |
| Focused or Other | The provider delivered the message to a named tab or filtered inbox experience             |
| Spam or junk     | The provider classified the message as unwanted or suspicious                              |
| Not received     | MailSlurp did not observe the message at that seed during the test window                  |
| Pending          | The provider result is still being checked                                                 |

A promotional or filtered-tab result is delivered, but it is different from primary placement. Judge the outcome against the purpose of the message.

## Step 9: Review content and domain issues

Open **Content issues** for message-level findings and **Domain issues** for sender and sending-domain checks. Use the result to select a specific correction:

- verify SPF, DKIM, and DMARC alignment for the Braze sending domain
- confirm the visible From address and reply handling
- remove broken, redirected, or unnecessary links
- keep text, images, and alternative text balanced
- preserve a clear unsubscribe and preference path
- avoid sudden volume changes or unengaged customer audiences
- retest the complete revised Braze campaign with a fresh run

Do not change several unrelated variables and then compare the scores as if they were the same test.

## Braze inbox placement checklist

Before treating a run as valid, confirm:

- the marker and seed addresses came from the active MailSlurp run
- the Braze Seed Group contains exactly four current provider seeds
- old test addresses and customer addresses were removed
- the normal campaign audience is restricted to controlled QA users
- the marker appears in every email variant
- the final sender, sending domain, IP pool, content, and links were used
- Preview & Test was completed with representative profile data
- the campaign summary shows the intended Seed Group
- all MailSlurp provider rows belong to the current run
- content and domain issue tabs were reviewed before retesting

## Troubleshooting Braze placement tests

### MailSlurp does not recognize the Braze campaign

Confirm that the exact active marker appears in the subject or body of the delivered seed copy. Check every Braze variant and create a new MailSlurp run if an old marker was sent.

### Fewer than four seed copies arrive

Compare the Braze Seed Group with the current MailSlurp address list. Confirm that all four Braze user profiles have the correct email addresses and that the intended Seed Group was attached to the campaign.

### The campaign could reach customers

Stop before launch and replace the normal campaign audience with a controlled internal QA segment. A placement test should not use a production customer segment.

### The subject begins with [SEED]

That prefix is expected for Braze Seed Group copies. Keep the MailSlurp marker elsewhere in the subject or message body so the run can still match the email.

### A provider stays pending

Wait for the observation window to finish. A delayed or not-received target is evidence from the test and should not be replaced with an assumed placement.

### A content score looks good but placement is poor

Content checks do not reproduce every provider's filtering, reputation, engagement, and historical signals. Use the provider placement rows, authentication results, list quality, sending pattern, and content together.

## FAQ

### How do I test Braze inbox placement?

Create a MailSlurp placement run, put its four current addresses in a Braze Seed Group, add the unique marker to the campaign, attach the group in Target Audiences, launch to a controlled QA audience, and review the provider rows.

### What is a Braze Seed Group?

A Seed Group is an Internal Group whose members receive a copy of each campaign email variant. It is useful for internal monitoring and controlled inbox placement tests.

### Is Braze deliverability the same as inbox placement?

No. Delivery indicates that the receiving system accepted the email. Inbox placement identifies the folder or category where a controlled provider seed observed the message.

### Can Braze test Gmail Promotions and Outlook spam placement?

Yes. A MailSlurp placement run includes controlled provider seeds and reports observed outcomes such as primary, promotions, focused, spam, or not received.

### Should I use a Content Test Group or Seed Group?

Use a Content Test Group for preview and personalization review in **Test Send**. Use a Seed Group for provider placement because Braze attaches seed copies to the campaign during audience targeting.

For visual QA, follow the [Braze Gmail, Outlook, iPhone, and Android preview guide](/guides/braze-device-rendering/). The dashboard steps and result definitions are also available in the [inbox placement documentation](/docs/inbox-placement/).