I have a user who continually gets the D004 error when accessing their archive. I restored it from backup, it works for a little while then this happens again.

Upon restoring from the backup this time I have run a GWCheck on it - it reported 492 Error 50's for orphaned blob files.

I've since then mucked around with it a little more and done a structural rebuild just to see what happens. I have the archive in backup anyway so no problems mucking around to see what happens.

A few questions have arisen from this situation though -

1. There's seemingly no way to recover the orphaned blob files, so how can you ever possibly know that someones archive/mailbox has this issue?

It seems to be something that happens, then builds up causing more issues over time (that you don't see on the surface) and eventually presents itself in such a way that you need to restore from backup - but there's no way of telling whether the backup has these issues already held within it (although it works regardless until the same thing inherently happens again).

2. Is there a way to catch this early and prevent this from happening?

3. Can I empty all working mail from a backed up archive into the mailbox, then re-archive to a new location to create a new archive?