A laudable suggestion but how is Germany handling Instant Messaging that has almost the capability of e-mail? For anybody who works in large organizations today, they know that young people who start their careers only have email as a way to apply for jobs, as a way to register for services and communicate with their grandparents.
There is no way that a company can block the transfer of data from smart phone email to IM. Email will probably decline in use as the technology is replaced by more advanced communication models over the next 5 years with fewer controls over content or data paths eventually going the way of the fax or inter-office memo.
If the security and regulatory specialists  haven’t figured a way to keep this animal in its cage what makes anything think that laws like this will be effective? It is known in IT that as soon as a system is completed and training provided that the next information being communicated and shared is how to workaround and game the system.