LARGE single-system Cyrus installs?

[Vincent Fox]

Wondering if anyone out there is running a LARGE Cyrus
user-base on a single or a couple of systems?

Let me define large:

25K-30K (or more) users per system
High email activity, say 2+ million emails a day

We have talked to UCSB, which is running 30K users on a single
Sun V490 system.  However they seem to have fairly low activity
levels with emails in the hundred-thousands range not millions.

So far that's the only other place we've talked to.  Everyone else
seems to spread out 5K users on a large number of backends.

We have 60K users, and were trying to run them spread across
2 systems and ran into problems when Fall quarter started and
the load just skyrocketed.  Email volume today 3.6 million.