SOLVED, maybe: mail no longer vanishes, but new problems abound.
My mail no longer vanished overnight.
The big clue to the problem came when someone changed my root password.
I presume someone had broken into my system and had been deleting
the administrator's mail (mine) to evade discovery. At some point
the invadoer got too bold and changed the root password.
As soon as I noticed this, I took my machine offline and began a
reinstall from scratch.
I'm not finished yet, but email is working and I'm running with
a 2.2 woody kernel.
I've encountered several problems which I will be mentioning in
more detail in later posts:
The sarge installer (admittedly from a pre-stable release) did
not work. I suspect it did not recognise my IDE controller
hardware. Lacking net connectivity because of the breakin,
I could not download a newer installation CD.
The woody installer worked fine, but I still haven't got
woody to recognise my second hard drive. It seems to be
complaining about 127 beind an invalid number og heads.