Hello @KaliR7. While doing a live send of the email to just yourself and/or anyone else who will be looking over the email will fully verify how it will look once it goes out to your contacts, you can also send a test preview of your email to test the formatting across different devices. This way, the test email will send usually within a few minutes and you can view your email both on your desktop and your mobile device! The email will also stay in a draft status so you can still scheduled it out to your contacts.
However, if you do the live send and confirm the formatting, you will have to make a copy of the sent email before sending it. I apologize for any frustration this may have caused you.