Draft a message with AI
Ask Sendly's assistant to write a message for a mailbox — a new email from a short brief, a rewrite of something you already have, or a set of subject lines.
It returns text and sends nothing. The response always reports sent: false, and there is no argument that changes that. Putting a draft in someone's inbox is a separate operation (sendMailboxMessage) under a separate scope, so a client that may draft is not thereby a client that may mail your customers.
That is also why this operation asks only for mailboxes:read: it names a mailbox so the draft can be written in that address's voice, reads no correspondence, and stores nothing.
Everything you pass — the brief, the draft, the recipient context — is treated strictly as data describing what to write, never as instructions to the model.
Drafting is capped at 120 requests per hour per project.
Requires the mailboxes:read scope — View the mailboxes on your domains and their settings.
API key authentication. Use a sk_* (FULL) or pk_* (SENDING_ONLY) key as the bearer token. Public keys (pk_*) are restricted to the email-send endpoints and the self-serve list subscribe/unsubscribe pair; every other endpoint — event tracking included — answers 403 for them. In scope terms (used by /api/v1/* operations): FULL keys hold every scope; SENDING_ONLY keys hold only emails:send.
In: header
Path Parameters
Request Body
application/json
TypeScript Definitions
Use the request body type in TypeScript.
Body for POST /api/mailboxes/{id}/drafts — ask for help writing, never for sending.
Response Body
application/json
application/json
application/json
application/json
application/json
application/json
application/json
application/json
curl -X POST "https://example.com/api/mailboxes/497f6eca-6276-4993-bfeb-53cbbbba6f08/drafts" \ -H "Content-Type: application/json" \ -d '{ "mode": "draft" }'{
"success": true,
"data": {
"subject": "string",
"body": "string",
"subjects": [
"string"
],
"sent": false
}
}{
"success": false,
"error": {
"message": "string",
"code": "string",
"details": {
"errors": [
null
]
}
}
}{
"success": false,
"error": {
"message": "string",
"code": "string",
"details": {
"errors": [
null
]
}
}
}{
"success": false,
"error": {
"message": "string",
"code": "string",
"details": {
"errors": [
null
]
}
}
}{
"success": false,
"error": {
"message": "string",
"code": "string",
"details": {
"errors": [
null
]
}
}
}{
"success": false,
"error": {
"message": "string",
"code": "string",
"details": {
"errors": [
null
]
}
}
}{
"success": false,
"error": {
"message": "string",
"code": "string",
"details": {
"errors": [
null
]
}
}
}{
"success": false,
"error": {
"message": "string",
"code": "string",
"details": {
"errors": [
null
]
}
}
}