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POST
/
audience
/
contacts
/
lists
/
bulk
Bulk attach contacts to lists
curl --request POST \
  --url https://app.lettr.com/api/audience/contacts/lists/bulk \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "contact_ids": [
    "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  ],
  "list_ids": [
    "3c90c3cc-0d44-4b50-8888-8dd25736052a"
  ]
}
'
{
  "message": "Contacts attached to lists.",
  "data": {
    "attached": 1,
    "already_attached": 1,
    "total_pairs": 1
  }
}

Documentation Index

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

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Attach every combination of contact_ids × list_ids (up to 1000 contacts × 50 lists). Existing pairs are reported in already_attached. 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 attach/detach contacts to/from lists. All combinations of contact_ids × list_ids are processed.

​
contact_ids
string<uuid>[]
required
Required array length: 1 - 1000 elements
​
list_ids
string<uuid>[]
required
Required array length: 1 - 50 elements

Response

OK

​
message
string
required
Example:

"Contacts attached to lists."

​
data
object
required