The answer is: Add the email address !!
If you are writing an important email. One you have spent more than 20 minutes writing and you have the time. Write the damn thing, save it as a draft, and, more than a few hours later, THEN put the email address in and hit send.
There is always a risk you send the email by mistake and cannot get that back. This is a lesson we all learn the hard way but we need not. If you can configure a delayed send in your email then do it. 45 seconds is more than enough to spot any mistake but don’t use it as a crutch. But if you remember one thing from me it is add the email address last.
Hearty handshakes from me to you