The client runs MS Exchange 5.5 on NT4. (Not exactly, but nearly -- it's MS SBS 4.5)
Yesterday lunctime, their disk died. It made funny noises. NT would not boot. And so they called me.
So today I've been rebuilding their server on a fresh disk (about twice the size, yaay) from a collection of partial NTBACKUP backup tapes from the past couple of weeks.
NTBACKUP says nice friendly things like "Well, Priv.EDB was corrupt before it was backed up -- but I restored it anyway." On every tape they posess, going back many weeks. I think this disk of theirs has had bad blocks for quite a little while.
None of the Priv.EDB files would permit the MSExch Information Store to start cleanly.
Nevertheless, because I am the brilliant Exchange internals wizard that I am, they seem now to have a clean, consistent, stable information store containing all the messages up to about 11:50 pm on March 1st. And their domain's SAM, and the registry, and all sorts of other unlikely-looking always-online data structures, are clean, consistent and stable too.
Time to re-admit TCP port 25, I think.