Users recently reported the situation to Macworld, noting that instead of relegating the possibly pornographic emails to a spam folder, iCloud is “pre-filtering” or automatically deleting the messages with no notification to sender or recipient. When a user tries to send an email containing words such as “barely legal”, iCloud will automatically block the message. Apple responded, saying, “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.”

As part of the iCloud’s Terms and Conditions, the company notes that it can pre-screen or otherwise modify content at any time: You acknowledge that Apple is not responsible or liable in any way for any Content provided by others and has no duty to pre-screen such Content. However, Apple reserves the right at all times to determine whether Content is appropriate and in compliance with this Agreement, and may pre-screen, move, refuse, modify and/or remove Content at any time, without prior notice and in its sole discretion, if such Content is found to be in violation of this Agreement or is otherwise objectionable.

iCloud’s so-called “silent email filtering” raises questions as to the reliability of Apple’s service as an inadvertent phrase flagged by the spam blocking system could cause a user to never receive a message. The situation is concerning given both iCloud users and senders have no way of knowing an email was not received as the messages are simply deleted.

Other services, like Google’s Gmail, Yahoo Mail or Microsoft’s Outlook, are not known to have such measures in place and funnel spam into appropriately tagged folders.