I have a unique issue where I exported PSTs of some users with each mailbox size over 4GB by using Exmerge and I was surprised to see the exported PST sizes were the original size in the exchange system manager. Today when I tried to so the same the exported PST size is only 2GB. I am not getting any errors but the original size is larger in system manager.
I have exchange 2003 and I am using Exmerge. I am aware of 2GB limitation on PST.
I am not sure if microsoft has fixed this limitation on SP3 or any hotfix.