smtpserver and load averages

[Michael Scott Shappe <mss1@cornell.edu>]

Today, we had a prolonged outage on our central e-mail server,
cornell.edu, due to hardware failure. When I brought the machine back and
restarted ZMailer, the load shot through the roof due to a flood of
inbound smtpserver connections.

I've managed to cobble together a version of smtpserver that refuses
connections when the load average climbs above a command-line-set
threshold. 

My code currently parses the output of uptime, rather than determining the
values directly; attempts to link Sun's /lib/libkvm.a with smtpserver
resulted in the time() (3) function crashing the program with an Illegal
Instruction error; for reference, this happened even if NO kvm-related
code was actually called. This appears to be Sun's bug, and there's even a
README out there describing a patch for SunOS 4.1.3, but the patch does
not appear to exist anywhere.

At any rate, Matti, could you look into adding some sort of load-limiting
ability to smtpserver at your level? 

Mikey