This is something that Freshdesk just added as well. They let you set a delay in the settings 5,10,20, or 30 seconds before the email goes out and added an undo button on emails and SMS messages that were sent out manually. I'd love to see this in conversations on GHL.

"I just sent out an email as my Agency admin that should have been from my business email instead... :( "

For people managing multiple businesses / sub accounts, this would be a life saver!