Outlook 2007 Generates double network traffic when sending attachm

[Jimmen]

When sending a 2MB file I notice that it first sends a little over 2MB to
exchange server, and then after a few seconds it sends another 2 MB
(Taskmanager/Networking/Bytes sent). Anyone know why?
Outlook 2007 cached mode on XP against Exchange 2003, all SP:s and updates.

 

[Jimmen]

I got an answer from MS that this is normal behaviour for Outlook 2003/2007
in cached mode against Exchange 2003. It first sends the message, then copies
it to the .ost file, and then syncronizes the .ost file to the server. Thus
creating double amount of network traffic for every message. If Dynamics CRM
4 outlook client is installed it can generate up to 4 times network traffic
depending on setup.
Upgrade to Exchange 2007 should solve the issue.