This will make me unable to moderate, but what the hell?
Brown had a unix based backend for years. A few years back, they got a new IT head, who insisted on off-the-shelf packages for everything. So out went postoffice, and in came Exchange. It's been running Exchange since then, and yes, untold numbers of problems (though nothing like this). We're not even on the most recent version of Exchange, which will make my office's future transition to Snow Leopard problematic since afaik the native Mail interoperability with Exchange that comes in 10.6 won't work with anything but the latest.
AFAIK, the plan is to move everyone to Google eventually, departments too. Once they get all the security figured out. This isn't helping, of course.