Take Cisco.com for example. There are a lot of systems there that are sending out emails. Employees and newsletters are probably encrypted but only make up a sm

Take Cisco.com for example. There are a lot of systems there that are sending out emails. Employees and newsletters are probably encrypted but only make up a small portion of their outbound mail. Things like ticket updates are going to result in a huge volume of email. Cisco may have (wrongly) decided that because the ticketing system is a trusted source it doesn't need to be encrypted. So some of their email is going directly out from the tool and some is going through a smart host. This is probably why it's <50%.