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POST
/
conversations
/
conversations
/
2026-09-beta
/
threads
/
{threadId}
/
messages
Send a message to a thread
curl --request POST \
  --url https://api.hubapi.com/conversations/conversations/2026-09-beta/threads/{threadId}/messages \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "attachments": [
    {
      "fileId": "<string>",
      "type": "FILE"
    }
  ],
  "channelAccountId": "<string>",
  "channelId": "<string>",
  "recipients": [
    {
      "deliveryIdentifiers": [
        {
          "value": "<string>"
        }
      ],
      "actorId": "<string>",
      "name": "<string>",
      "recipientField": "<string>"
    }
  ],
  "senderActorId": "<string>",
  "text": "<string>",
  "type": "MESSAGE",
  "richText": "<string>",
  "subject": "<string>"
}
'
import requests

url = "https://api.hubapi.com/conversations/conversations/2026-09-beta/threads/{threadId}/messages"

payload = {
    "attachments": [
        {
            "fileId": "<string>",
            "type": "FILE"
        }
    ],
    "channelAccountId": "<string>",
    "channelId": "<string>",
    "recipients": [
        {
            "deliveryIdentifiers": [{ "value": "<string>" }],
            "actorId": "<string>",
            "name": "<string>",
            "recipientField": "<string>"
        }
    ],
    "senderActorId": "<string>",
    "text": "<string>",
    "type": "MESSAGE",
    "richText": "<string>",
    "subject": "<string>"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)
const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    attachments: [{fileId: '<string>', type: 'FILE'}],
    channelAccountId: '<string>',
    channelId: '<string>',
    recipients: [
      {
        deliveryIdentifiers: [{value: '<string>'}],
        actorId: '<string>',
        name: '<string>',
        recipientField: '<string>'
      }
    ],
    senderActorId: '<string>',
    text: '<string>',
    type: 'MESSAGE',
    richText: '<string>',
    subject: '<string>'
  })
};

fetch('https://api.hubapi.com/conversations/conversations/2026-09-beta/threads/{threadId}/messages', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));
<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api.hubapi.com/conversations/conversations/2026-09-beta/threads/{threadId}/messages",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'attachments' => [
        [
                'fileId' => '<string>',
                'type' => 'FILE'
        ]
    ],
    'channelAccountId' => '<string>',
    'channelId' => '<string>',
    'recipients' => [
        [
                'deliveryIdentifiers' => [
                                [
                                                                'value' => '<string>'
                                ]
                ],
                'actorId' => '<string>',
                'name' => '<string>',
                'recipientField' => '<string>'
        ]
    ],
    'senderActorId' => '<string>',
    'text' => '<string>',
    'type' => 'MESSAGE',
    'richText' => '<string>',
    'subject' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.hubapi.com/conversations/conversations/2026-09-beta/threads/{threadId}/messages"

	payload := strings.NewReader("{\n  \"attachments\": [\n    {\n      \"fileId\": \"<string>\",\n      \"type\": \"FILE\"\n    }\n  ],\n  \"channelAccountId\": \"<string>\",\n  \"channelId\": \"<string>\",\n  \"recipients\": [\n    {\n      \"deliveryIdentifiers\": [\n        {\n          \"value\": \"<string>\"\n        }\n      ],\n      \"actorId\": \"<string>\",\n      \"name\": \"<string>\",\n      \"recipientField\": \"<string>\"\n    }\n  ],\n  \"senderActorId\": \"<string>\",\n  \"text\": \"<string>\",\n  \"type\": \"MESSAGE\",\n  \"richText\": \"<string>\",\n  \"subject\": \"<string>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}
HttpResponse<String> response = Unirest.post("https://api.hubapi.com/conversations/conversations/2026-09-beta/threads/{threadId}/messages")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"attachments\": [\n    {\n      \"fileId\": \"<string>\",\n      \"type\": \"FILE\"\n    }\n  ],\n  \"channelAccountId\": \"<string>\",\n  \"channelId\": \"<string>\",\n  \"recipients\": [\n    {\n      \"deliveryIdentifiers\": [\n        {\n          \"value\": \"<string>\"\n        }\n      ],\n      \"actorId\": \"<string>\",\n      \"name\": \"<string>\",\n      \"recipientField\": \"<string>\"\n    }\n  ],\n  \"senderActorId\": \"<string>\",\n  \"text\": \"<string>\",\n  \"type\": \"MESSAGE\",\n  \"richText\": \"<string>\",\n  \"subject\": \"<string>\"\n}")
  .asString();
require 'uri'
require 'net/http'

url = URI("https://api.hubapi.com/conversations/conversations/2026-09-beta/threads/{threadId}/messages")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"attachments\": [\n    {\n      \"fileId\": \"<string>\",\n      \"type\": \"FILE\"\n    }\n  ],\n  \"channelAccountId\": \"<string>\",\n  \"channelId\": \"<string>\",\n  \"recipients\": [\n    {\n      \"deliveryIdentifiers\": [\n        {\n          \"value\": \"<string>\"\n        }\n      ],\n      \"actorId\": \"<string>\",\n      \"name\": \"<string>\",\n      \"recipientField\": \"<string>\"\n    }\n  ],\n  \"senderActorId\": \"<string>\",\n  \"text\": \"<string>\",\n  \"type\": \"MESSAGE\",\n  \"richText\": \"<string>\",\n  \"subject\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body
{
  "archived": true,
  "attachments": [
    {
      "fileId": "<string>",
      "type": "FILE",
      "name": "<string>",
      "url": "<string>"
    }
  ],
  "channelAccountId": "<string>",
  "channelId": "<string>",
  "client": {
    "integrationAppId": 123
  },
  "conversationsThreadId": "<string>",
  "createdAt": "2023-11-07T05:31:56Z",
  "createdBy": "<string>",
  "id": "<string>",
  "recipients": [
    {
      "deliveryIdentifier": {
        "value": "<string>"
      },
      "actorId": "<string>",
      "name": "<string>",
      "recipientField": "<string>"
    }
  ],
  "senders": [
    {
      "actorId": "<string>",
      "deliveryIdentifier": {
        "value": "<string>"
      },
      "name": "<string>",
      "senderField": "<string>"
    }
  ],
  "text": "<string>",
  "type": "MESSAGE",
  "inReplyToId": "<string>",
  "richText": "<string>",
  "status": {
    "failureDetails": {
      "errorMessageTokens": {},
      "errorMessage": "<string>"
    }
  },
  "subject": "<string>",
  "updatedAt": "2023-11-07T05:31:56Z"
}
{
  "message": "Invalid input (details will vary based on the error)",
  "correlationId": "aeb5f871-7f07-4993-9211-075dc63e7cbf",
  "category": "VALIDATION_ERROR",
  "links": {
    "knowledge-base": "https://www.hubspot.com/products/service/knowledge-base"
  }
}

Supported products

Authorizations

​
Authorization
string
header
required

The access token received from the authorization server in the OAuth 2.0 flow.

Path Parameters

​
threadId
integer<int64>
required

The unique ID of the thread.

Body

application/json
​
attachments
(FILE · object | QUICK_REPLIES · object | SOCIAL_MEDIA_METADATA · object)[]
required
​
channelAccountId
string
required
​
channelId
string
required
​
recipients
object[]
required
​
senderActorId
string
required
​
text
string
required
​
type
enum<string>
default:MESSAGE
required
Available options:
MESSAGE
​
richText
string
​
subject
string

Response

successful operation

​
archived
boolean
required
​
attachments
(FILE · object | LOCATION · object | CONTACT · object | UNSUPPORTED_CONTENT · object | MESSAGE_HEADER · object | QUICK_REPLIES · object | WHATSAPP_TEMPLATE_METADATA · object | SOCIAL_MEDIA_METADATA · object)[]
required
​
channelAccountId
string
required
​
channelId
string
required
​
client
object
required
​
conversationsThreadId
string
required
​
createdAt
string<date-time>
required
​
createdBy
string
required
​
direction
enum<string>
required
Available options:
INCOMING,
OUTGOING
​
id
string
required
​
recipients
object[]
required
​
senders
object[]
required
​
text
string
required
​
truncationStatus
enum<string>
required
Available options:
NOT_TRUNCATED,
TRUNCATED,
TRUNCATED_TO_MOST_RECENT_REPLY
​
type
enum<string>
default:MESSAGE
required
Available options:
MESSAGE
​
inReplyToId
string
​
richText
string
​
status
object
​
subject
string
​
updatedAt
string<date-time>
Last modified on March 31, 2026