I get asked about this a lot, and even though I’ve blogged about this in the past, people still think it’s OK to put your PST’s on the network somewhere. Well don’t! I’ve dug out the kb article that explains why we don’t support them. These sort of things will happen…
All operations take longer.
Write operations can take approximately four times longer than read operations.
Outlook has slower performance than the Exchange Client.
For the reasons mentioned above, Offline Folders (.ost) files and personal address book (.pab) files on a network share that are accessed remotely are also unsupported configurations. If you do have roaming users, have a look at the link to the Office resource kit for some tips on strategies for Outlook roaming, and configuring roaming users for Outlook..