This free feature allows you to retract an email for up to 30 seconds after you have sent it. In every Office 365 account, you can opt in to an undo send feature.

Recall an Office 365 email with undo send. Top Tips and Tricks for Microsoft Outlook 2016. Recall is only works if the recipient hasn't opened the email. In the dialog box that appears, search for a 'Recall' message (please see the screenshot below), and you will see the original message above it. In Outlook 2016, Outlook 2019 and Office 365, you can also go to the Deleted Items folder and click the Recover items recently removed from this folder link at the top.