Hi back at you,
We like to say that we're actually using "placeholders" rather than stubs, because the portion of the message that stays in the Exchange Server is the same as the one that was there before.
If you have the outlook add-in installed (strongly recommended) the end-user experience is transparent when accessing archived messages. When a user selects an archived message in outlook the full message is displayed in the preview pane without any intervention. There is also a search integrated into outlook allowing the user to search the full text of all
their messages - archived or not - in one place.
(There's also an add-in for OWA which displays the full message in place of the placeholder too
The best way to see this is to have a look at our videos of the experience
. Or if you want get in touch and we can give you a quick 1:1 demo.
The archived messages and attachments are stored as files on disk (using a proprietary file format) and the archive stores can be moved around as you require by attaching and detaching archive stores to machines with storage services on them. At any point in time you can use the ability to "Copy Back to Exchange Server" to un-archive messages back to users mailbox.
If you really want to get a detailed introduction to our technology be sure to read the Technical Overview
Hope that helps - I know I've rambled a bit