IMHO the biggest benefit having a caching mailbox is that end users can enjoy the windows client event on networks with poor connections. (Slow bandwidth, packet losses, server outages, etc)

Unfortunately the caching mailbox has its limitations. I've summarised our major wishes regarding the caching mailbox.
Usually our major goal is to simplify administration, because we have over 50k mailboxes.

- Administrators are unable to control the location of the cache folder from the GW Admin Console. There should be settings for the caching mailbox in GWAC so the admin can lock down, set up initial setting for it, using windows macros for the location would be the best. This idea:

- Nuisance with password change. After the end user has changed his password, they don't understand why they have to log in to the caching mailbox with their old password and then give GW the new password again. Also if they type the new password instead of the previous one, they cannot log in and the result is a help desk call. This process is simply too long for end users who are not trained, lots of things can go wrong. It would be much easier if the GW client would check the typed in password against the live server also, and if the password is accepted, then the GW client would change the password of the cache in the background without any user intervention.

- Administrators are unable to see the status/health of the cache. Are the indexes okay? Are there any database problems? On server side the scheduled gwchecks are fixing potential problems, and reporting errors to the Notify users. If GW cannot self fix the problem, than the administrator has the chance to fix the problem, because he was notified about it. But as far as I know the caching mailbox does not have any scheduled events for this. The administrator meets the problem only when there are end user complains. And then it is too late.

- In the GW client display a more visible notification about the status/freshness of the caching mailbox. End users are always curious about the status of their outgoing emails. The caching mailbox does not provide a highly visible indication of that. I know that there is the "Last Connection: Timestamp" in the corner. When they are online they think that everything is okay. But when in caching mode, they are mistrusting the client. Maybe a greed dot in the bottom left corner could indicate that the caching mailbox has nothing to deliver, everything is up to date, the last synchronization to the server was okay. A yellow dot could indicate that there are messages waiting for delivery or the last synchronization to the server failed. I know that the client sends everything as soon as the Send button got clicked. But end users need a more visible, more simpler feedback.