Duplicate Messages in Sendblue: Workflow Fired More Than Once or Same Contact Re-Enrolled?
Last updated: April 12, 2026
Last Updated: April 12, 2026
Customer-Facing Guide
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If the same contact receives the same or nearly identical message multiple times, the cause is usually a workflow or automation firing more than once — not a random duplicate for no reason.
The most common causes
More than one automation is listening for the same event.
The same contact got re-enrolled into the same workflow.
A retry or timeout rule fired the same action more than once.
Two different systems are both sending the same message.
A webhook or API request is being triggered repeatedly upstream.
What to check first
Look at the exact contact that received the duplicates.
Check whether the message body is exactly the same each time or slightly different.
Check whether the sends happened within seconds, minutes, or after a trigger repeated later.
Check whether the contact is enrolled in more than one workflow that could send the same message.
Check whether the same event can fire in more than one place (CRM, workflow tool, Zapier, Make, webhook, etc.).
Fast interpretation guide
| Pattern | What it usually means |
|---|---|
| Exact same message sent within seconds | The workflow or upstream trigger probably fired more than once. |
| Same message sent from two different automations | You likely have overlapping workflow logic. |
| One contact keeps getting re-hit after status changes | The contact may be re-entering the workflow when a field/tag changes. |
| Only one workflow execution is visible but duplicates still happened | Support may need to inspect the underlying request flow. |
What to send support if you need help
The affected contact and message examples
Approximate timestamps
Which workflow/tool you think fired
Whether the contact might have been re-enrolled or retriggered