Trigger fetchmail on client-side Imap-refresh

[m00nraker [m00nraker@gmx.net]]

Hi there.

My Kolab 3 Server runs on local CentOS 6.4 installation. 

My question is about Kolab-Cyrus and fetchmail.

E.g., I got 5 Kolab-users, each of them uses 3 external Pop3 mailboxes at different provider (GMail and GMX). At the moment, I configured fetchmail running as a demon service. It pulls in all mail from the external Pop3-accounts for each Kolab-user and delivers the mail to Cyrus Imap. The pull in interval is set to 15 minutes. This works, but I want it different, more user controlled:

Using e.g. Rouncubemail as the mail frontend, there is a refresh-button, to refresh the Inbox and get new mail from the local Kolab (Imap-) server. When a Kolab user starts refreshing the inbox, I would like to automatically trigger a fetchmail script on the Kolab server. So fetchmail should not run as a demon service any more but on demand. So, refreshing the inbox on the client-side should automatically start a fetchmail script on the server-side. When the fetchmail-job is done, the inbox should be refreshed at the client side. When the external mailboxes got new mail, the kolab-Roundcubemail user only has to click on the inbox refresh-button and then Kolab-Server automatically pulls in all external mail and then refreshes the inbox from the Kolab user. Hope u understand, what I mean. 
I don't know, where exactly I have to put a fetchmail-script on the server to fetch new mail from external mailboxes when doing an Imap-refresh on the client-side...
Is someone there who can help me to realize this? 

Thanks, Kai