Then provide useful, technically complete, secure alternatives that are vetted by the government. The expectations of your employees are changing, so the technology you provide should change along.
The article says: The Düsseldorf newspaper Handelsblatt said Kelber, previously a Social Democrat (SPD) federal parliamentarian, was reacting to complaints from citizens about the use of WhatsApp by unnamed federal authorities.
It seems some „authorities” used it as a citizen communication channel for official contact.
Unfortunately the agencies in charge of vetting this kind of software work in timespans of 2-3 years (not just Germany in most other countries as well).
