/usr/lib/x86_64-linux-gnu/libesmtp.so.6 is in libesmtp6 1.0.6-4.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/lib/x86_64-linux-gnu/libesmtp.so.6.1.6
/usr/lib/x86_64-linux-gnu/libesmtp.so.6.1.6