I've been administering EMC's EmailXtender for the past 6 months. I haven't been doing too much with it. It was initially setup by an EMC implementation engineer. I setup a server connected to several LUN's on an EMC Clarion SAN for the hardware. It was initially sized for 7 years of retention.
On the client side the integration with Outlook is almost seamless. Especially with Outlook 2007. The only way you can tell an email has been shortcuted is to look at the message class. You can add it as a column, the message class reads IPM.Note.ExShortcut.owa.
On the server side the EmailXtender makes archival and shortcut of email amazingly simple. I have taken a store 275GB in size and reduced it to 40GB. Reversed the process and reduced it again down to 80GB. Why did I do this? The initial shortcut had the criteria of older than 30 days and pre-pending the subject line with Archive Message. I had to reverse this in order to change the criteria. There was no adverse affects on the Exchange server.
As a last step, I created a new message store in Exchange 2003 enterprise and moved the shortcut mailboxes to the new store. This allowed me to reduce the store size while minimizing downtime to the mailbox move. Imagine the downtime if I performed an offline defrag on a 275GB information store.
