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POST
/
audience
/
contacts
/
bulk
Bulk create contacts
curl --request POST \
  --url https://app.lettr.com/api/audience/contacts/bulk \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "emails": [
    "jane@example.com",
    "joe@example.com"
  ],
  "list_id": "3c90c3cc-0d44-4b50-8888-8dd25736052a",
  "properties": {}
}
'
{
  "message": "Contacts created successfully.",
  "data": {
    "created": 2,
    "already_existed": 0
  }
}

Documentation Index

Fetch the complete documentation index at: https://docs.lettr.com/llms.txt

Use this file to discover all available pages before exploring further.

Create up to 1000 contacts in a single request. Emails are normalized and deduplicated; contacts that already exist are reported in already_existed. Requires the audience:write scope and is blocked for sandbox API keys.

Authorizations

​
Authorization
string
header
required

API key for authentication

Body

application/json

Bulk create contacts. Emails are normalized (lowercased, trimmed) and deduplicated.

​
emails
string<email>[]
required
Required array length: 1 - 1000 elements
Maximum string length: 255
Example:
["jane@example.com", "joe@example.com"]
​
list_id
string<uuid> | null

Optional list to add all contacts to

​
properties
object

Custom property values applied to every contact created in this batch

Response

Contacts created

​
message
string
required
Example:

"Contacts created successfully."

​
data
object
required