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POST
/
v1
/
email-messages
/
{id}
/
preview
Send a preview of an email message
curl --request POST \
  --url https://app.loops.so/api/v1/email-messages/{id}/preview \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "emails": [
    "<string>"
  ],
  "contactProperties": {},
  "eventProperties": {},
  "dataVariables": {}
}
'
{
  "id": "cmn5zia4i0017tzli8ric8giv"
}
Content API endpoints are currently in beta and are subject to change.
Send a test email message to one or more addresses. Accepted variable fields depend on the parent’s type:
  • Campaign accepts contactProperties.
  • Workflow accepts contactProperties and eventProperties.
  • Transactional accepts dataVariables.
Supplying a field the parent cannot reference results in a 400 Bad Request error. Each team can send up to 100 preview emails per day.

​
Request

​
Path parameters

​
id
string
required
The ID of the email message.

​
Body

​
emails
string[]
required
One or more addresses to send the preview to.
​
contactProperties
object
Contact property values to render. Accepted for campaign and workflow previews.
​
eventProperties
object
Event property values to render. Accepted for workflow previews only.
​
dataVariables
object
Transactional data variables to render. Accepted for transactional previews only.

​
Response

​
Success

​
id
string
required
The ID of the email message the preview was sent for.

​
Error

If the request body is invalid or a variable field the parent cannot reference was supplied, a 400 Bad Request is returned. If the daily preview limit (100 per team per rolling 24 hour window) was reached, a 429 Too Many Requests is returned. A 404 Not Found is returned if the email message does not exist. If the API key is invalid (or content API is not enabled for your team), a 401 Unauthorized is returned.
​
message
string
required
An error message describing what went wrong.
{
  "id": "cmn5zia4i0017tzli8ric8giv"
}
Last modified on June 22, 2026