email statistics (number of mails and in MB) per mailbox per domain - ISPConfig3, Debian 7

Hello!
I followed Perfect Server tutorial for ISPConfig 3, nginx, Dovecot: https://www.howtoforge.com/perfect-server-debian-wheezy-nginx-bind-dovecot-ispconfig-3
I was wondering if there is a way to see e-mail statistics per mailbox and per mail domain.
Something like 'Mail traffic' (on 'Email' tab, under 'Statistics'), but that shows only in MB.
Manual says:

I'm confused now. I use Dovecot and it DOES show statistics but the manual clearly states that it only shows statistics if one uses Courier.

 

So, manual just isn't updated? That's fine.
But what about my main question?
Is there an option or some kind of add-on or anything that could display the number of sent/received mail per mailbox and per mail domain?

 

I've done some googling and Logwatch looks promising.
Do you have any other suggestion?