There are pros and cons to Apple’s walled garden approach in iOS. It’s an advantage when one is concerned with viruses and malware, but it can also be a hassle when dealing with specific file types. Until recently, you couldn’t really do anything with a .zip file on iOS, at least not without jailbreaking your device.
Now, the company which has been around since my first Windows 95 machine, has developed an iOS app that allows you to open Zip attachments through email, or view Zip files even if encrypted. You can even copy all the contents of a Zip file, if in plain text, to the clipboard, to use in another app.
There is a long list of file types you can preview — .txt, .doc, .docx, .xls, .xlsx, .ppt, .pptx, .rtf, .pdf, .key, .numbers, .pages, .htm, .htm, .jsp, .bmp, .jpg, .jpeg, .tif, .tiff, .png, .gif — making WinZip extremely useful for those situations where you just have to see what’s in an email.
Check out WinZip for iOS (iPad an iPhone compatible) in the App Store.