/usr/lib/libkmailprivate.so.4 is in kmail 4:4.14.1-1+deb8u1.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/libkmailprivate.so.4.14.2
/usr/lib/libkmailprivate.so.4.14.2