Scheduling & canceling sends
Schedule for later and recall a send before it leaves.
Any send can be scheduled for the future with scheduled_at. Until a message is handed to the provider it sits in a scheduled (or queued) state and can be canceled.
A single email
From the dashboard, open the email on the Emails page and click Cancel. Via the API, PATCH /api/v1/emails/{id} with { "cancel": true }. You can also reschedule a still-pending email by PATCHing a new scheduled_at.
A whole batch
POST /api/v1/emails/batches/{id}/cancel stops every still-scheduled message in the batch. Already-sent messages are unaffected. In the dashboard this is the Cancel batch button under Emails → Batches.
Once it's out, it's out
After a message has been handed off for delivery it can no longer be recalled. Cancel only works while a send is still scheduled or queued.