You'll need to look on the App Store for a compatible app. There are many apps available already that are capable of viewing EML files. Once installed on your device, you should be able to open the files in the app that you installed.
Thanks for your reply. I was using such an app but it's an extra app to open. It would be easier when the content would be visible in Dropbox. Now I am making a PDF of each mail, but that's also a time consuming action.
Do you work or study in the creative industry? If so, which area?