Hi, @TraceTheStar 
This one is a bit of an adventure for sure. Fortunately, everything we need is in the Conversations inbox and messages APIs (BETA).
Our clue was down the page a bit “When you make a successful request, the response will include the thread ID, which you can use to retrieve, update, or create a new message in a thread.” Retrieve threads.
My quick test is likely different than you, but I think the underlying approach will get what you are after.
Request 1 — Get threadId
GET /conversations/v3/conversations/threads
The response includes a property called id which is actually the threadId in this case
My request
curl --request GET \
--url https://api.hubapi.com/conversations/v3/conversations/threads \
--header 'authorization: Bearer YOUR_ACCESS_TOKEN'
My response
HTTP 200
{
"results": [
{
"id": "3016120935",
"createdAt": "2022-08-11T23:26:58.904Z",
"status": "OPEN",
"latestMessageTimestamp": "2022-08-11T23:28:36.188Z",
"latestMessageSentTimestamp": "2022-08-11T23:28:36.188Z",
"latestMessageReceivedTimestamp": "2022-08-11T23:26:58.969Z",
"assignedTo": "A-10233975",
"spam": false,
"inboxId": "124212669",
"associatedContactId": "551",
"archived": false
},
{
"id": "3016291208",
"createdAt": "2022-08-11T23:23:48.172Z",
"status": "OPEN",
"latestMessageTimestamp": "2022-08-11T23:23:54.489Z",
"latestMessageReceivedTimestamp": "2022-08-11T23:23:54.489Z",
"spam": false,
"inboxId": "124212669",
"associatedContactId": "1",
"archived": false
},
{
"id": "3016313742",
"createdAt": "2022-08-11T23:24:36.472Z",
"closedAt": "2022-08-11T23:25:46.568Z",
"status": "CLOSED",
"latestMessageTimestamp": "2022-08-11T23:24:36.689Z",
"latestMessageReceivedTimestamp": "2022-08-11T23:24:36.689Z",
"assignedTo": "A-10233975",
"spam": false,
"inboxId": "124212669",
"associatedContactId": "1",
"archived": false
}
],
"paging": {
"next": {
"after": "MzAxNjMxMzc0Mg%3D%3D",
"link": "https://api.hubapi.com/conversations/v3/conversations/threads?hs_static_app=endpoint-reference-ui&hs_static_app_version=1.974&after=MzAxNjMxMzc0Mg%3D%3D"
}
}
}
Request 2 — Get messageId
We can take the value for “id”: “3016120935” and get the associated messages from this endpoint:
GET /conversations/v3/conversations/threads/{threadId}/messages
My request
curl --request GET \
--url https://api.hubapi.com/conversations/v3/conversations/threads/3016120935/messages \
--header 'authorization: Bearer YOUR_ACCESS_TOKEN'
My response
HTTP 200
{
"results": [
{
"id": "d3295feca7814dc0806ae1c96636d705",
"createdAt": "2022-08-11T23:28:36.188Z",
"updatedAt": "2022-08-11T23:28:36.188Z",
"createdBy": "A-10233975",
"client": {
"clientType": "HUBSPOT"
},
"senders": [
{
"actorId": "A-10233975"
}
],
"recipients": [
{
"actorId": "V-551",
"deliveryIdentifiers": []
}
],
"channelId": "1000",
"channelAccountId": "79569651",
"archived": false,
"text": "this is a test",
"richText": "<div style=\"text-align: left\">this is a test</div>",
"attachments": [],
"truncationStatus": "NOT_TRUNCATED",
"status": {
"statusType": "SENT"
},
"direction": "OUTGOING",
"type": "MESSAGE"
},
{
"id": "56b8f95f373149afa3cffaf6dddf1825",
"createdAt": "2022-08-11T23:28:10.344Z",
"updatedAt": "2022-08-11T23:28:10.344Z",
"createdBy": "A-10233975",
"client": {
"clientType": "HUBSPOT"
},
"senders": [
{
"actorId": "A-10233975"
}
],
"recipients": [
{
"actorId": "V-551",
"deliveryIdentifiers": []
}
],
"channelId": "1000",
"channelAccountId": "79569651",
"archived": false,
"text": "hello",
"richText": "<div style=\"text-align: left\">hello</div>",
"attachments": [],
"truncationStatus": "NOT_TRUNCATED",
"status": {
"statusType": "SENT"
},
"direction": "OUTGOING",
"type": "MESSAGE"
},
{
"id": "4a41191f2a0d406ebb208e06f42559b3",
"createdAt": "2022-08-11T23:27:57.101Z",
"updatedAt": "2022-08-11T23:27:57.101Z",
"createdBy": "A-10233975",
"client": {
"clientType": "HUBSPOT"
},
"senders": [
{
"actorId": "A-10233975"
}
],
"recipients": [
{
"actorId": "V-551",
"deliveryIdentifiers": []
}
],
"channelId": "1000",
"channelAccountId": "79569651",
"archived": false,
"text": "hellp",
"richText": "<div style=\"text-align: left\">hellp</div>",
"attachments": [],
"truncationStatus": "NOT_TRUNCATED",
"status": {
"statusType": "SENT"
},
"direction": "OUTGOING",
"type": "MESSAGE"
},
{
"id": "75dd0ade-60ca-4952-a49b-fc8fa94f7f92",
"createdAt": "2022-08-11T23:26:59.661Z",
"createdBy": "S-hubspot",
"client": {
"clientType": "SYSTEM"
},
"senders": [],
"recipients": [],
"archived": false,
"assignedTo": "A-10233975",
"type": "ASSIGNMENT"
},
{
"id": "1c83f851-4814-4ce5-93b2-ef17b54ac339",
"createdAt": "2022-08-11T23:26:59.621Z",
"createdBy": "S-hubspot",
"client": {
"clientType": "SYSTEM"
},
"senders": [],
"recipients": [],
"archived": false,
"newStatus": "OPEN",
"type": "THREAD_STATUS_CHANGE"
},
{
"id": "7c5bbeb0801f455c95b3e6fd85cc7d3d",
"createdAt": "2022-08-11T23:26:58.969Z",
"updatedAt": "2022-08-11T23:26:58.969Z",
"createdBy": "V-551",
"client": {
"clientType": "SYSTEM"
},
"senders": [
{
"actorId": "V-551"
}
],
"recipients": [],
"channelId": "1000",
"channelAccountId": "79569651",
"archived": false,
"text": "Hello",
"richText": "<div>Hello</div>",
"attachments": [],
"truncationStatus": "NOT_TRUNCATED",
"status": {
"statusType": "RECEIVED"
},
"direction": "INCOMING",
"type": "MESSAGE"
},
{
"id": "e5a4bc4685d74194becd81f8fdc03748",
"createdAt": "2022-08-11T23:26:58.967Z",
"createdBy": "S-hubspot",
"client": {
"clientType": "SYSTEM"
},
"senders": [
{
"actorId": "S-hubspot"
}
],
"recipients": [
{
"actorId": "V-551",
"deliveryIdentifiers": []
}
],
"channelId": "1000",
"channelAccountId": "79569651",
"archived": false,
"text": "Got any questions? I'm happy to help.",
"type": "WELCOME_MESSAGE"
}
],
"paging": {
"next": {
"after": "MTY2MDI2MDQxODk2Ny0w",
"link": "https://api.hubapi.com/conversations/v3/conversations/threads/3016120935/messages?hs_static_app=endpoint-reference-ui&hs_static_app_version=1.974&after=MTY2MDI2MDQxODk2Ny0w"
}
}
}
Essentially, you’ll need one call to get the threadIds and a second to get the messageIds. With that information, you can follow the documentation to retrieve messages.
Have fun coding! – Jaycee