I have a colleague who has a brilliant attitude to email.
He has two key automatic filters:-
CC - "Thank you for CCing me to this email. In line with my personal effectiveness policy, I review CC'd email around once a quarter. It may be up to 90 days before your email is reviewed."
Out of Office - "Thank you for your email, as I am now on holiday until xx/xx/xxxx, it has been automatically deleted. If you believe the matter is still pertinent after xx/xx/xxxx then I invite you to resend the email for my review."