We are running Zimbra 5.0.4, We had a few users still running pre version 5 of the Zimbra/Outlook ZCS connector up until today. We discovered a major issue related to this. When users started complaining of poor network performance, we installed a sniffer and noticed two users were flooding our network. The traffic was between their machine and our Zimbra server. In short, what happened is at some point they tried to send a large attachment that exceeded the allowable size set in Zimbra.
Our mailbox.log had entries in the log every few minutes all day for these two users that stated: ..."ua=Zimbra-ZCO/4.5.190 (5.1.2600 Service Pack 2;; en-US);] FileUploadServlet - Exceeded maximum upload size of 20480000 bytes: org.apache.commons.fileupload.FileUploadBase$SizeL imitExceededException: the request was rejected because it's size exceeds allowed range"
After we upgraded the connectors for these two users, everything is back to normal. Just information that could come in handy. Another good reason to keep all connectors updated.
Big Rock Sports