BOTH APPLE’S MAIL app and Messages have become more tolerant of human error, in letting you unsend when you want. These work quite differently: Mail does this by delaying dispatch of messages by up to 30 seconds, during which you can change your mind; Messages still sends immediately, but gives you up to 15 minutes to cancel or correct each message.
1 Send it later
Schedule your email to be sent in the future, rather than trying to remember to send
