Maybe. I feel like the spam number is misleading because OK, maybe the 70% of emails are spam, but spam is smaller than real traffic so it's not 70% of the size of the stored corpus. Also nobody stores spam, they delete it.
Two organizations where I've worked at (1000s of people) managed their own email infrastructure, with their own spam filter.. it ranged from 70% to 75% of incoming emails.
Most spam emails are just a few words of plaintext, I'm surprised too the size of the stored corpus is spam in the same percentage. It seems like a few emails with medium-large attachments would outnumber the spam content which should be in the kbs/email at most.
