It was only a few days ago that a major issue in iOS 7 was discovered that left e-mail attachments unencrypted. The issue is present in iOS 7.0, all the way up to the most recent iOS 7.1.1, and was discovered by a security researcher known by the name of Andreas Kurtz.
Apple is reportedly aware of the issue
, although they haven't yet presented a fix to the public even though the company says they are working on one. On the other hand, if you want to get yourself protect