Undo send

If you send an email and need to recall it for further editing, the Undo Send feature gives you 15 seconds to do so.

After you send an email, you can undo this action within 15 seconds by clicking Undo in the prompt at the bottom of the screen. You can also press the z key if you have keyboard shortcuts enabled.

You will be returned to the Compose screen to continue editing your email.

The send can be undone up to 15 seconds after the message is sent. After 20 seconds, the email will be delivered to the recipient.

If you would like to disable this feature, you can do so by following these steps:

  1. Go to Settings → Signature & Compose.
  2. Click the Compose options tab.
  3. Under Undo send, select Send messages immediately.

Once this feature has been disabled, your messages will be immediately sent and delivered without a 20 second delay.


  • The Undo Send feature is available only in the Fastmail web interface or on the official Fastmail mobile app. It can't be used with third party email clients.
  • After 15 seconds have passed, it is not possible to undo the message sending.
  • If you have Undo Send enabled, emails that are sent via the Fastmail web interface or the mobile app will be delayed by 20 seconds.
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