This would be a way to be able to copy a link when sending an email in order to merge it later on to another email.
Here is an example on how this would be used :
  1. Customer asks for ETA from Brand X
  2. You send email to Brand X about ETA (Send & Copy)
  3. You merge email from Customer with the one to Brand X
  4. You snooze email (unsnooze with reply)
  5. When Brand X replies, your email is unsnoozed and you can select Customer message and reply to email with information on hand.
This saves a lot of time versus Sending email, then going to "Sent", copying email link, going back to Customer email and merging both.