To add, the SAF is not just a pure BlackBerry tax. Without getting too deep into it, there's stuff that needs to be set up with the carrier, and that's why BlackBerry push was a true push back in the day, without the phone burning through both battery and data. And when this gear malfunctions, you'd know, because you're not getting push at all.

They sipped battery and data, and once that gear is setup, the SAF was very profitable.

Even to this day, email is not the same level of instant.