From Zarafa wiki

To get an overview of the zarafa-client versions connected to the server one can use <tt>zarafa-stats</tt> and some smart use of GNU tools. This can be useful to check if the auto updater is working in your network. Below are two examples.

Versions by IP

zarafa-stats --session | egrep "0x6743001E|0x674F001E" | awk {'print $2'} | sed '$!N;s/\n/ /' | sort -n | uniq

Versions by user

zarafa-stats --session | egrep "0x674F001E|0x6701001E" | awk {'print $2'} | sed '$!N;s/\n/ /' | sort -n | uniq

Note that it is just the matching key name in the <tt>egrep</tt> command which is different.