According to this report, Apple is now not only spam-filtering out emails containing particular phraseology (in this case, "barely legal teens"), but deleting them entirely, whether they're being sent to your account, or from your account. And what's even more interesting, apparently iCloud users agreed to give Apple that kind of power.
The precedent here is dangerous, and one that needs to be carefully examined--if corporations are going to exercise the ability to investigate/examine (even from an automated tool) the email that you're sending or receiving, then technically privacy is being violated. This has always been an issue with email--corporations have always maintained that email sent on their servers to their employees is their property, and the legal world has held that up to be the case (which is the same rationale that then gives DOJ and other prosecutors the right to examine corporate email in order to see if there's been any wrongdoing taking place, so this is a good thing). But when you're not an employee of the corporation, does the fact that the email travels through their servers mean that they have the right to view your email, even through an algorithm? Does an ISP have the right to read its subscribers' email, too? The fact that iCloud users agree to allow Apple this power is an interesting twist, but frankly the courts have seen fit to throw out waivers that were deemed unenforceable or illegal, so that's something of a red herring, I think.
The much deeper issue here is one of privacy: how much privacy is really left to us these days? And, speaking for myself, why don't more people care?
This also has me wondering if, maybe, email and Internet services haven't reached a level of ubiquity that suggests that they should be considered part of the national or state infrastructure--as in, should local/city/state/federal government maintain an email infrastructure (servers) with the same degree of privacy guarantees that they held up for the US Postal Service? Or, maybe even, should the US Postal Service be that entity?