The answer is simple. You just can’t do it on iPhone. It’s trivial you can attach any types of files when using email on desktop. On iPhone, however, Apple only allows you to attach photos and videos in your email.
The recent release of a cydia tweak called AnyAttach tries to break this limitation. As the name suggests, AnyAttach tweaks the built-in Mail app and enables it to accept any types of email attachment.
How to Use AnyAttach to Attach File
Installation of AnyAttach is very straightforward. Just launch cydia and search for AnyAttach to install it. Like other jailbreak hacks, AnyAttach does not add any icon on home screen. It simply tweaks the native Mail app and adds a “paper clip” icon in the subject field. Whenever you want to attach a file, tap that icon and you can select any file from the file browser.
AnyAttach supports both iPhone and iPad. Of course, your device should be jailbroken before you can utilize the hack.
AnyAttach is now available on Cydia store for $1.99. If you need to attach other file types such as Word document, PDF or Excel file, you can take a look at AnyAttach.