Question : Problem with OST Files for Cached Mode

I have a user who needed to be able to open Outlook at home to sync with their Treo.

Rather than try to explain whole concept of offline/offline and syncing, I decided to set them up in Cached mode, as they have a broadband connection and VPN into the exchange server.

The user has a 750Mb mailbox, which I really don't want to sync over the internet, so I connect one of the users computers on the LAN to their mailbox and enabled cached mode there.

Once replication was finished, I copied the OST file to a USB Key, took it back to my office, setup the profile on a computer there, VPN'd in and tested it. This worked fine.

The next day, I drove out onsite, copied the same OST file to that computer and setup an Outlook profile.

When I tried to launch outlook in Cached mode, it gave me the error:

"Outlook is using an old copy of your Offline Folder file (.ost). Exite Outlook, delete the .ost file, and restart Outlook. A new file will be automatically created the next time you initiate a send/receive."

This just has an OK button. Outlook continues to load, but does not automatically update folders. I can do a send and receive, which will bring new mail in.

If I turn off cached mode and open Outlook offline, I get the error "Unable to open your default e-mail folders. Outlook is using an old copy of your Offline Folder File(.ost). Exit Outlook, delete the .ost file, and restart Outlook. A new file will be automatically created the next time you initiate a send/receive."

Does anyone know what causes this? It seems like this is the logical way to roll out a cached mode environment to remote users with large mailboxes, which is a scenario I have in my near future. If sometimes they will fail liek this, I will need to rethink that strategy.

Answer : Problem with OST Files for Cached Mode

OST files are linked to both an Outlook profile and an Exchange mailbox. Change either of these and you cannot open it.
This is a security "feature" to keep someone from making a copy of your OSt file and opening it on another machine.

How you were able to do this on your machine in your office is beyond me.

If you are using Exchange 2003 why not enable RPC over HTTPS?