Averages are fairly useless - use median instead. If you look at a
flat average on a typical workload, you will find that the average is
determined by a very small number of messages taking days to be
delivered to some dial-up system or other. One day the users in
question sign off, your average is halved and management
congratulates you for having solved the problem without a costly
hardware upgrade. On the other hand, it is meaningful to know
that 98% of the messages are delivered in under a minute and
90% in under 6 seconds. The "slow destinations" factor is usually
between 1-2% in a typical Internet environment, it should be much
lower for intranet distributions (hopefully!)

  Eric