> Unless you have a really low budget, I'd recommend going with Sun/Solaris
> rather than Linux.

I think you have a slightly different version of 'low budget' than a lot of
us here. :)
for most of the places I've worked, 'low budget' means '< $100'; I suspect
your version may differ from mine by an order of magnitude or two. :)

I haven't worked with Solaris to any real degree; so the fact that I've
never seen a Solaris box crash doesn't mean anything. OTOH; I've not seen
a Linux box running a stable kernel verifiably crash[1]; where it wasn't the
fault of hardware, or the administrator doing something stupid [2]. (I
temper this with the statement that I'm relying on my memory for this; which
is a notoriously bad thing to do).

[1] There were a couple of boxes at a co-lo running 2.2.14 which became
unresponsive (after having been up for 400+ days, I think); and the guy at
the co-lo said there was a bunch of stuff on the screen when he hooked up a
monitor to it, so he was told to power-cycle it; after which point (and a
kernel upgrade) the boxes have been up ever since. Some similar boxes at the
same place were up for 500+ days until the kernels were upgraded.

[2] I *have* crashed a stock RH 2.2.14 kernel a couple of times, by running
it out of memory (sometimes deliberately). that kernel didn't like it very
much when I did a 'swapoff' on swap space that was in use, either. ;> 
	that said, *no* OS currently existing, deals well with Out Of Memory
conditions.

as for Sun hardware; I've seen enough Sparcs go bad, that I don't put a
world of faith in the claims that it's substantially better than x86
hardware. I can't argue that it's a much better architecture (better
processor design, openboot ROM kicks ass); and they usually do use
better-quality components; but it still obeys the rule that for the last 5%
more performance, you pay 50% more.

for the mail relay situation:
I say use a K7 box with a pile of memory and a few IDE drives (do software
RAID on them if you like). SCSI drives are better; but with memory as
obscenely cheap as it is these days; the data probably won't need to be
lastingly written to disk, if the box is just a mail relay, so the
performance differences between SCSI and IDE will probably be less
important. (tho don't take my word as gospel).

Carl Soderstrom
-- 
Network Engineer
Real-Time Enterprises
(952) 943-8700