How to Test Kit Inbox Placement and Spam Score

Kit inbox placement testing measures where a real marked campaign lands after it is sent. MailSlurp supplies current controlled seed addresses across Gmail, Google Workspace, Outlook, and Microsoft 365, matches the message using a unique marker, and reports inbox, tab, spam, or not-received outcomes with content and domain diagnostics.

Quick answer

1. Create a new MailSlurp inbox placement test.
2. Copy its unique marker and current seed addresses.
3. Choose Download CSV for your mail provider, select Kit, and download the provider-ready file.
4. Import the CSV into a dedicated Kit tag.
5. Add the exact marker to the campaign subject or body.
6. Send the final campaign only to the dedicated tag.
7. Return to MailSlurp, get the score, and wait for the run to complete.
8. Review the percentage, provider rows, content issues, and domain issues.

Create a fresh run for every campaign revision. The marker and seed list identify one specific test.

Before you begin

Configure Kit's required mailing address and verified sending address, then use a dedicated tag containing only controlled MailSlurp seeds.

Use the sender, sending domain, subject, preview text, links, images, footer, subscription settings, and unsubscribe behavior planned for the campaign. Do not include customers or old seed addresses in the test audience.

Why this Kit audience model is used

Kit stores subscribers in one audience and uses tags and segments for organization. Importing the current seeds under a dedicated tag, then replacing All Subscribers with that tag in the Broadcast filter, keeps the live send restricted to the controlled test audience.

See the Kit Broadcast documentation for the provider's current setup terminology and prerequisites.

Step 1: Create a fresh MailSlurp placement run

Open Inbox placement and create a test. Copy the unique marker and current provider seed addresses.

Never copy seed addresses or a marker from an older run or tutorial screenshot. The active values are what let MailSlurp associate the delivered messages with this result.

Step 2: Download the Kit CSV

Next to the mailto action, choose Download CSV for your mail provider. Select Kit, review the import instructions, and download the file. The exported rows use headers recognized by Kit and contain only the current MailSlurp seeds.

Step 3: Import the current seeds into Kit

1. Open Grow > Subscribers, choose Add Subscribers, and upload the Kit CSV.
2. Map Email address and First name, then apply a dedicated inbox placement tag during import.
3. Wait for the tag count to update and verify that every current seed is present.

Keep this tag isolated. Remove expired seeds from earlier tests so the member count and active run remain unambiguous.

Step 4: Add the exact marker

Add the MailSlurp marker exactly as shown to the campaign subject or body. A clear subject pattern is:

Kit inbox placement test mip-example123

Keep the marker unchanged if Kit adds its own test prefix or tracking parameters.

Step 5: Send to the controlled seed audience

Create or duplicate a Broadcast, add a recipient filter for the dedicated tag, remove the All Subscribers filter, keep the active MailSlurp marker unchanged, and send once.

Confirm the send is accepted and that the recipient count matches the current MailSlurp seed list.

Step 6: Wait for the placement result

Return to the active MailSlurp run and get the score. Keep the result open until the observation window completes and the progress indicator reaches its final state.

Do not infer a missing provider result. Let the observation window resolve it as received or not received.

Step 7: Interpret the result

Result	Meaning
Primary or inbox	The provider placed the campaign in its main inbox experience.
Promotions	The message was delivered to a promotional category.
Focused or Other	The message was delivered 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 promotion or filtered-tab result is delivered, but it is different from primary placement. Evaluate the result against the campaign's purpose.

Step 8: Review content and domain issues

Open Content issues for message-level findings and Domain issues for sender and sending-domain checks. Use those findings to make a specific correction:

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

Kit inbox placement checklist

• The marker and seeds came from the active MailSlurp run.
• The Kit CSV was downloaded for the current run.
• The dedicated tag contains every current seed and no customer contacts.
• The marker appears unchanged in the subject or body.
• The final sender, domain, content, and links were used.
• The recipient count matches the MailSlurp seed count.
• Kit accepted the send.
• The MailSlurp progress indicator reached its final state.
• Provider placement, content issues, and domain issues were reviewed.

Troubleshooting

MailSlurp does not recognize the campaign

Confirm the exact active marker appears in the delivered subject or body and that the current seed addresses were used.

The imported seeds are missing

Reopen the Kit tag, check field mappings and consent status, and wait for any asynchronous import or member-count refresh to finish.

Fewer results appear than expected

Confirm the campaign recipient count matched the seed count and that the run is still active. Keep the result open until the observation window resolves every target.

The campaign lands in spam

Review the provider row together with content and domain issues. Correct one meaningful variable at a time, then create a fresh run and send the complete revised campaign.

FAQ

What is a Kit inbox placement test?

It is a controlled send of the final Kit campaign to MailSlurp seed inboxes so you can observe destination folders across Gmail and Microsoft mailbox families.

Is a spam score the same as inbox placement?

No. Content and authentication checks identify risk signals; placement testing records what happened to the marked campaign at the controlled mailbox providers.

Can I reuse an old seed list?

Use the marker and seed addresses shown by the active run. A fresh run keeps the campaign revision and its evidence clearly connected.

Should the placement and device-preview emails be combined?

Keep them separate. A render address produces client screenshots, while a marked seed list produces provider placement observations.

After placement review, use the Kit device preview guide to inspect the delivered design across Gmail, Outlook, iPhone, Android, and desktop clients.