Apple's iCloud service will silently discard emails containing words or phrases Apple has chosen to ban:
A reader called Steven G. alerted Macworld sister site, Infoworld, to the issue. His email goes to some length to explain how he discovered that the phrase was banned:

Steven G says: "A screenwriter was delivering a PDF attachment of a draft of his script to the project's director, by emailing it from his iCloud/MobileMe account to Gmail. The problem? The script would never arrive, no matter how many times he would send it. But sending other PDF documents worked fine."

He began experimenting with the file, turning the screenplay to a PDF and ZIP and then encrypted the file using Apple's encrypted archive format. But it came with an unusual "Not Virus Scanned" message appended to the subject field. He began to suspect that something inside the file was failing and then started to cut it into smaller parts to send it.

Steven G. writes: "AND THEN I SAW IT -- a line in the script, describing a character viewing an advertisement for a pornographic site on his computer screen. Upon modifying this line, the entire document was delivered with no problem."
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