Some acquisitions make sufficiently little sense when taken at face value that they signal a major future direction, are mostly about acquiring specific talent or technology, or are just utterly misconceived. Dropbox’s acquisition of the company behind the Mailbox iPhone app falls into one of those categories, but it’s unclear which just yet, given that making a quirky iOS email client seems far from Dropbox’s core mission. Despite protestations that the Mailbox app will continue, it seems entirely possible that it could share the fate of the Sparrow email app, which, while still for sale, is no longer being developed after its developers joined Google in July 2012.

There’s nothing all that new here — Apple has long deleted some email messages silently, even including TidBITS at various times — but Dan Moren and Lex Friedman show how iCloud can delete messages containing certain phrases with no warning to the user, even if the phrase occurs only in a zipped PDF attachment. So if something you’re expecting doesn’t show up (assuming you notice), consider asking your correspondent to send it to another email address.