If I add an email to an automation, will contacts who have already entered the automation receive it?

If the email is below the contact's current position in the automation, the email will be sent to them. If the contact has completed and exited, or if the contact's position is below the email step, they will not receive the email.

If a contact has completed your automation before you added your email, you can re-add that contact to a specific point in your automation so that they receive your communication and go through the rest of your automation steps. This help article will walk you through how to do that.