I posted a similar question almost a month ago.
In this time I did not any step forward

.
I searched for files containg the words size or limit in /opt/zimbra (and its descedants,) but I had no luck.
I expose again in two words my issue: in the system where I am developing all works fine but in the production server when I try to upload video files (20MB or so) it doesn't work while a short text file is receveid correctly.
I thought it is a simple config issue. I am quite surprised nobody had the same problem in the past.
The development machine has Ubuntu while the server has a Fedora Core.
I hope somebody can save me.
Thanks
PS A firewall?