Attachments

Files pass through Plum's attachment safety checks. A file rejected by those is reported per file rather than failing the request, because the message itself is still sent — so check the success flag on every entry.

Like a plain reply, sending attachments marks the conversation read.

Sending

Send multipart/form-data with a Body field and one Attachments field per file:

POST /v2/messaging/conversations/23722/messages/attachments
Authorization: Bearer {token}
Content-Type: multipart/form-data

Body=Here are the check-in instructions.
[email protected]
[email protected]

Limits

At least 1 file — a request with none is a 400 pointing you back at the plain reply route

Up to 10 files per message
Up to 20 MiB (20971520 bytes) per file
.jpg, .jpeg, .png, .pdf or .docx only

A file of the wrong type or over the size limit fails the whole request with 400, naming the offending file by its position — for example Attachments[1].

Request

Field	Type	Description
`body`	string	The text of the message. May be empty when the files are the point of the reply
`Attachements`	file	One field per file, repeated. At least one is required

Response

Field	Type	Description
`messageId`	integer	The message the files were sent on. Downloads need it
`name`	string	The name you uploaded the file under, and the one shown to a person
`fileName`	string	The name the file is stored under. Downloads use this, not name
`contentType`	string	Media type of the stored file
`size`	string	Size of the file in bytes, sent as a string rather than a number
`success`	boolean	Whether the file passed Plum's attachment safety checks
`errors`	boolean	Why a file did not pass, and empty for one that did

{
  "messageId": 325926,
  "attachments": [
    {
      "name": "directions.pdf",
      "fileName": "04de6d75-91e5-42ad-9c8e-82e003e85f4b.pdf",
      "contentType": "application/pdf",
      "size": "190",
      "success": true,
      "errors": []
    }
  ]
}

Downloading

GET /v2/messaging/conversations/{conversationId}/messages/{messageId}/attachments/{fileName}

Returns one file. Use the fileName from the response, not the original name:

GET /v2/messaging/conversations/23722/messages/325926/attachments/04de6d75-91e5-42ad-9c8e-82e003e85f4b.pdf
Authorization: Bearer {token}

The file is returned as-is, byte for byte, with its stored content type and a Content-Disposition header naming it. A file whose type Plum cannot determine comes back as application/octet-stream.

Response

Status	When it happens
`200`	Sending: the message was created, and every file is reported separately in `attachments`. Downloading: the file follows
`400`	No files, more than 10 files, a file too large, a file type not allowed, or the token carries no usable user id
`401`	The `Authorization` header is missing, malformed or expired
`404`	No conversation with that id belongs to the authenticated host, or that message has no file stored under that name
`5xx`	A transient failure reaching the messaging back end.

A 200 on the send route does not mean every file arrived. It means the message was created — the per-file success flags say which files went with it.