Apple is apparently performing some content-based iCloud e-mail filtering, resulting in e-mails that never arrive to their intended destination. As detailed by Macworld, e-mails that included a particular phrase, even in a zipped PDF file, were prevented from getting to the intended recipient. This was regardless of whether the message was from a known sender, indicating that Apple is placing a pretty judging eye on what passes through its servers.

The issue came to light when users began noticing that e-mails with the words "barely legal teen" were having trouble arriving in their iCloud inboxes from outside senders. E-mails with the phrase in the body, an attached PDF, or a zipped attached PDF were never delivered or even returned to the sender. Instead, they simply disappeared into the ether of a nebulous black box of a filter that Apple has never made known to its iCloud customers. E-mails sent from iCloud accounts with that phrase, however, made it through, as did replies to iCloud-sent e-mails that contained the phrase.

Apple acknowledged the existence of the filter, telling Ars (and Macworld), "Occasionally, automated spam filters may incorrectly block legitimate email. If the customer feels that a legitimate message is blocked, we encourage customers to report it to AppleCare.”

But, as Macworld points out, the problem is precisely that these e-mails are blinked out of existence the second they’re sent. Customers have no way of knowing what they're not receiving unless the sender manages to follow up via another medium, or with more e-mails that don’t contain trigger phrases.

We submit that the odds of a legitimate e-mail containing the phrase “barely legal teen” are low. But the surreptitious existence of the filter makes us wonder what else Apple is frowning upon from the dark of its data centers and silently swiping out of existence and into a trash bin, never to be seen again.