BB BlackBerry has discontinued BIS BlackBerry Internet Service a while ago. It did recently for BES BlackBerry Enterprise as well.
BlackBerry's main focus is providing highly secured services to companies, even though if they have lately released three BlackBerry devices on the Android platform.
Swisscom has also ceased servicing BlackBerry, because firstly it is costly to maintain a repair center just for BlackBerry, secondly most people have either moved to Android or iPhone.
Your BB BlackBerry 9900 is an old device in the digital world.
The closest smartphone platform you could get and be happy with is the iPhone IOS. It has tons of permissions, just like on a BB. Applications on iPhone are more stable, of better quality, more polished, launch faster and crash less on than those on Android. As for Windows Mobile/Phone, even though, it is a good smartphone and the O.S. Operating System is very stable, you will get yourself stuck with a very little choice of available applications.
To answer your question for the continued used of your e-mail, you should ask BlackBerry directly.