Gpg4KDE and GPG4win are approved for the transmission of classified information by the German Federal Office for Homeland Security.

The use of Gpg4KDE and GPG4win to encrypt Confidential Use Only (VS-NfD) messages (corresponding to EU RESTRICTED and NATO RESTRICTED) is approved by the German Federal Office for Homeland Security. It is now possible to use KMail to send messages encrypted by Kleopatra at the official level.

Source

Source: linux.org.ru