import { createClient } from "@mailsai/sdk";

const client = createClient(); // reads MAILS_API_KEY

const result = await client.messages.cancel(
  "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E",
);
console.log(result);

from mailsai import create_client

client = create_client()  # reads MAILS_API_KEY

result = client.cancel_message(
    "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E",
)
print(result)

curl -X POST 'https://api.mails.ai/v1/messages/msg_01JZX8K3M9Q4P7VN2YB6RTDC0E/cancel' \
  -H "Authorization: Bearer $MAILS_API_KEY"

mails emails cancel msg_01JABC

{
  "name": "mails_emails_cancel",
  "arguments": {
    "message_id": "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E"
  }
}

{
  "id": "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E",
  "status": "canceled",
  "canceled_at": "2026-10-04T12:00:00.000Z"
}

200  The canceled message.
400  Invalid request — malformed JSON or a field failed
     validation. Also feature_not_enabled when this
     server has a feature switched off (custom domains
     before they are available).
401  Missing or invalid API key.
403  The API key lacks the required scope
     (insufficient_scope), or the token belongs to an
     app connected by sign-in and this operation is
     closed to connected apps
     (connected_app_not_allowed).
404  Resource not found in this workspace, or the agent
     a send names is archived (agent_archived).
409  Conflict — duplicate resource, an in-progress
     idempotent request, a draft or scheduled message
     that started sending while it was being changed, or
     a thread deleted for good while one of its messages
     is being sent (duplicate_resource); or an agent
     name more than one agent has (agent_name_conflict:
     use the agent's id); or a status change on an
     archived agent, since archiving cannot be undone
     (agent_archived).
500  Internal server error.

Cancel a scheduled message

Cancels a send that is still scheduled, so it is never sent.

POST/v1/messages/{id}/cancelscope · manage

import { createClient } from "@mailsai/sdk";

const client = createClient(); // reads MAILS_API_KEY

const result = await client.messages.cancel(
  "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E",
);
console.log(result);

from mailsai import create_client

client = create_client()  # reads MAILS_API_KEY

result = client.cancel_message(
    "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E",
)
print(result)

curl -X POST 'https://api.mails.ai/v1/messages/msg_01JZX8K3M9Q4P7VN2YB6RTDC0E/cancel' \
  -H "Authorization: Bearer $MAILS_API_KEY"

mails emails cancel msg_01JABC

{
  "name": "mails_emails_cancel",
  "arguments": {
    "message_id": "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E"
  }
}

{
  "id": "msg_01JZX8K3M9Q4P7VN2YB6RTDC0E",
  "status": "canceled",
  "canceled_at": "2026-10-04T12:00:00.000Z"
}

200  The canceled message.
400  Invalid request — malformed JSON or a field failed
     validation. Also feature_not_enabled when this
     server has a feature switched off (custom domains
     before they are available).
401  Missing or invalid API key.
403  The API key lacks the required scope
     (insufficient_scope), or the token belongs to an
     app connected by sign-in and this operation is
     closed to connected apps
     (connected_app_not_allowed).
404  Resource not found in this workspace, or the agent
     a send names is archived (agent_archived).
409  Conflict — duplicate resource, an in-progress
     idempotent request, a draft or scheduled message
     that started sending while it was being changed, or
     a thread deleted for good while one of its messages
     is being sent (duplicate_resource); or an agent
     name more than one agent has (agent_name_conflict:
     use the agent's id); or a status change on an
     archived agent, since archiving cannot be undone
     (agent_archived).
500  Internal server error.

Path Parameters

idstringrequired

Sent message id with status scheduled.

Once the send starts going out it can no longer be canceled: the cancel changes nothing and answers 409 duplicate_resource, also when the send started while the cancel was running. A test key cannot cancel a send a live key scheduled (403 live_mode_required).

Response

idstring

Id of the canceled message (msg_…): the id in the path.

statusstring

Always canceled: the message will not be sent. Only a scheduled message can be canceled.

One of: canceled

canceled_atstring

When the send was canceled: the time of this request, also kept as the message's canceled_at.

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