Outlook desktop has the capability to hold mail for a few minutes before sending, just in case you change your mind. Gmail has Undo Send, giving you a few seconds to change your mind after hitting Send. Now Outlook on the web has the Undo Send capability as well.

This does not work like Recall Sent Message (which doesn't work very good); instead, the message is held for up to 30 seconds before it's sent, with a Sending Undo bar visible in the top right of the page if you change your mind about sending it. Similar to Gmail's Undo Send, which displays a link that disappears when the delay ends, Outlook on the web's uses an indicator bar so you can see how soon it will be sent.

To enable Undo Send, open Outlook on the web's Options and look for Undo Send under Automatic Processing section. Choose between 5, 10, 15 or 30 seconds. This feature is available in both business and consumer accounts.

To hold mail for a short period of time in Outlook on Windows desktop, create a rule with the 'Defer delivery by a number of minutes' action to hold mail in the Outbox for 1 to 120 minutes. For more information, see To delay sending a message in Outlook.