First
using the right permission your user will not have access to anything he is not supposed to.
second what you seems to ask is chroot. Currently your are able to chroot a user in ftp using remoteaccess contrib.
If you are not using sme10 pay attention that ftp is not using tls and password and traffic are not encrypted using ftp. starting sme10 default is to use tls.
if you choose nextcloud contrib, access to the ibay will be easy using the gui.
if you need scp or sftp see bug
https://bugs.koozali.org/show_bug.cgi?id=3178if you only want one ibay, it can be achieved with a few modifications : template custom and a cron to make sure /home/e-smith/ is root owned.