it could be useful to find large file by the command line
find / -type f -size +200'''M''' -exec ls -lh {} \; | awk '{ print $ ":_" $5 }';
use
‘k’ for Kilobytes (units of 1024 bytes)
‘M’ for Megabytes (units of 1048576 bytes)
‘G’ for Gigabytes (units of 1073741824 bytes)
else you can find more deeply
du -ah /var/lib/nethserver
and you can count how many files you have in a directory
find //var/lib/nethserver/vmail/ -type f | wc -l
more simply do
tree //var/lib/nethserver/vmail/