Prevent or Notify user when the same email is scheduled the same list in a short period

Submitting on behalf of a client.

This request is to add either a pop up notification when the same email is queued to the same list in a short period of time. Or to block this ability all together. The concern being, if the client accidentally, or another user, schedules an email out to the same list more than once, it can look like spammy behavior.