What "scheduled" means
When you click "Schedule" on an email campaign, the campaign is locked into a scheduled state and will send automatically at the time you selected. You can reverse this at any point before the send actually starts.
How to unschedule a campaign
Go to Email Campaigns in the left navigation.
Click the name of the campaign you want to cancel.
On the campaign detail page, you will see the scheduled send time listed, along with an Unschedule and Edit button.
Click Unschedule and Edit. A confirmation dialog will appear asking you to confirm.
Confirm the action. The campaign is immediately moved back to Draft status and the scheduled time is cleared.
From Draft, you can edit the campaign, pick a new send time, or leave it as a draft indefinitely.
Point of no return
The "Unschedule and Edit" button is only available while the campaign is in Scheduled status. Once the campaign transitions to Sending, Sent, or any other post-send status, the button is no longer shown and the sends cannot be stopped or recalled. Emails that have already left our servers cannot be retrieved from recipients' inboxes.
If you need to act quickly, open the campaign and look for the button as soon as possible. There is no way to cancel a campaign that is already sending.
If you do not see the "Unschedule and Edit" button
If the button is missing, the campaign has already started sending or has completed. Check the status shown on the campaign detail page. A campaign in Sending, Sent, Paused, Cancelled, or Failed status cannot be unscheduled.