Sending attachments in API V3 less than 3MB via JSON

In API V3, unlike previous versions, files/attachments are not uploaded separately but are directly attached when sending a message or creating a draft. This integration simplifies workflows by allowing attachments to be part of the initial message or draft creation process.

Attachment limits are 3MB for JSON.

To send emails larger than this you will need to send them as multipart, as a developer it might be easier to simply send all emails as Content-Type: multipart/form-data .


Both of the POST /v3/grants/{grant_id}/drafts and the POST /v3/grants/{grant_id}/messages/send endpoint supports attachments field.

Attachment field structure:

"attachments": [
    "content_disposition": "string",
    "content_type": "string",
    "filename": "string",
    "id": "string",
    "size": integer

Please note:  If the draft includes attachments. Must be Base64-encoded.



Was this article helpful?

0 out of 0 found this helpful

Have more questions? Submit a request



Please sign in to leave a comment.