The other thing, if some is in transit on the DAY, which ever day they choose, will they go ahead and let that package go on through? I mean it wasn't illegal to mail it two days previously, but it sits in a service center for one day, then is in transit for another day, then another service center.....
If the sender is not excitability "vape" or "Smoke" or "tobacco" or whatever, chances are slim they will find out.