Isn't the bigger problem that he gets about 5,000 emails in the first place? Maybe he was exadurting but I'm sure he gets more than his fair share and that's too much while on vacation but I bet he gets too much email while on the clock too.

I think he need an overall change in how many people email him and how he handles email while not on vacation as well as vacation. Deleting emails seems like a short term solution.