I've responded to any number of panicky calls this fall
about file space limits-- or, I should say, behavior
that is the result of folks bumping up against their
file space limits.
An auto-email would give the site owner a chance to
request more file space before her end-users (who are
uploading files via Data Tables) tell her the site's
broken.
A little higher up on the feature-request tree would be
the ability of the unit admin to modify the
auto-notification sent out from sites in her unit. One
unit admin might include her email address, another
might say to contact sitemaker@umich.edu, yet another
might say, "Sorry, that's all you get."