Get an SMS campaign's delivery report

GET

/api/v3/channels/{channelSlug}/letters/{letterUniqueId}/sms/delivery-report

curl --request GET \
  --url 'https://api.tryletterhead.com/api/v3/channels/example/letters/example/sms/delivery-report?api=true' \
  --header 'Authorization: Bearer <token>'

• Production

One SMS campaign’s delivery report for the campaign report’s Metrics chart: every recipient in exactly one of delivered / not delivered / pending / outcome unknown, the STOP replies attributed to the campaign, and the send’s state and rates. Counts only — no recipient identity ever appears in the response.

This endpoint is gated behind an internal feature flag that is not yet enabled for any tenant. While it’s off, the endpoint returns 404 Not Found.

v3 endpoints expect a company API key.

Authorizations

• bearerAuth

Parameters

Path Parameters

channelSlug

required

string

The newsletter’s channel identifier (slug).

letterUniqueId

required

string

Unique id of the SMS campaign (letter).

Query Parameters

api

required

boolean

Required. Set to true.

Responses

200

200 OK

Media type application/json

object

items

object

uniqueId

string

state

string

startedAt

string

completedAt

string

settled

boolean

recipients

integer

delivered

integer

notDelivered

integer

pending

integer

unknown

integer

unsubscribed

integer

deliveryRate

number

optOutRate

number

notDeliveredBreakdown

object

undelivered

integer

failed

integer

rejected

integer

skipped

integer

pendingBreakdown

object

held

integer

queued

integer

inFlight

integer

message

string

total

Always 1 for this endpoint.

integer

Example

{
  "items": {
    "uniqueId": "an-example-letter-uid",
    "state": "sent",
    "startedAt": "2026-09-15T14:00:00+00:00",
    "completedAt": "2026-09-15T14:05:00+00:00",
    "settled": true,
    "recipients": 1000,
    "delivered": 940,
    "notDelivered": 60,
    "pending": 0,
    "unknown": 0,
    "unsubscribed": 5,
    "deliveryRate": 0.94,
    "optOutRate": 0.005,
    "notDeliveredBreakdown": {
      "undelivered": 40,
      "failed": 15,
      "rejected": 5,
      "skipped": 0
    },
    "pendingBreakdown": {
      "held": 0,
      "queued": 0,
      "inFlight": 0
    }
  },
  "message": "Ok",
  "total": 1
}

404

404 Not Found — channelSlug doesn’t match a channel this company owns, the letter isn’t found on this channel, or the letter isn’t an SMS campaign.

Media type application/json

object

data

Array<object>

object

items

Array<object>

object

message

string

total

integer

Example

{
  "data": [],
  "items": [],
  "message": "Letter is not found on this channel.",
  "total": 0
}