Open Outlook and go to the Sent Items folder
Double-click the email you want to unsend
Select File
Select Info
Select Resend or Recall
Select Recall This Message
Choose Delete unread copies of this message or Delete unread copies and replace with a new message
Select whether to receive a notification for recall success or failure
Select OK
Note that recall only works if the recipient is using Microsoft Outlook within the same organization and has not read the email
If available, use Undo Send immediately after sending an email in Outlook on the web or new Outlook
Set the Undo Send delay in Outlook settings before sending future emails