imap_fetch_overview() increases traffic to NFS server

Hi, We have a linux server running a customised webmail application based on Horde. This server communicates with a seperate NFS server to access user's email data. We noticed that the traffic between the servers quickly rose from under 200k/s to 3Mb/s when we made some modifications and we found it was due to this function call: $mailList = imap_fetch_overview($stream, $messages, FT_UID); When we removed the FT_UID flag from the call the traffic returned to normal. I don't understand why this extra flag would cause such a huge rise in traffic- from what I understand this flag merely causes UIDs to be returned for the array of messages. The versions we are using are: Redhat Enterprise Linux ES Release 3 php 4.3.2-11 php-imap 4.3.2-11 Apache 2.0.46-32 Has anyone else had this problem? Is this a bug or am I doing something wrong? Thanks for your help! Kathie This message has passed through an insecure network. Please direct all enquires to the message author.