Maybe you’re trying to erase any lingering virtual sweet nothings of an ancient romance, or maybe you’re trying to wipe all sign of your top secret government job; whatever the case may be, you’d probably expect a deleted e-mail to stay deleted.

That’s just not the case with the current iPhone OS.

A fellow by the name of Matt Janssen was searching for something on his iPhone through OS 3.0′s new homescreen search when he noticed it: some of the results shouldn’t be there. Sure, they were relevant to the search keywords – but these results were emails that were supposed to have been deleted long ago.

So Matt ran another test: he sent himself an email, then deleted it from his iPhone. He cleared his trash, and then ran the search again. Sure enough, there it was. “Perhaps it’s being pulled from the server?”, he thought. So he deleted all trace of it from the server, and ran the search again. It still showed up. The iPhone was apparently caching old emails, with some as old as 4 months still popping up.

Always skeptical, we ran the same test ourselves. The first time around, all worked as one would expect. We deleted the email, cleared the trash, ran the search, and.. nothing. The email was gone. We were about to write it off as some sort of sham or fluke, when we ran the test a second time. On the second run through, everything happened just as Matt said it would; our once dead email had risen from the grave.

While the likelihood of someone nabbing your phone and guessing the subject line is arguable, the fact that such potential is there is bad enough. If you’re doing something you’re not necessarily supposed to be doing, the virtual fingerprint is but a quick search away – and all any potential sleuth needs is a bit of the subject line.

[Via Cult of Mac]