How do I delay all messages being sent by a set period of time (say 30 secs)?

I have the latest mac updates on on MacBook Pro. I am interested in setting a Mac Mail rule (cross all of my accounts) whereby when I press "send", Mail will hold the email for a set period (say, 30-sec) enabling me to catch any last seconds misses/issues/mis-spellings. I believe Gmail has this feature. Does anyone know how to set this rule?

Thanks,

Jack