In reply to Christopher Miller, re the tone of museum-l (and other) email
messages:
 
The 'imperative' is often simply part of the telegraphic style encouraged
by the medium.  It is also an appropriate voice to use in reply to simple
interrogatives (how can I... who knows about...).
 
Many replies are sent to the list simply because people either con't know
how to reply privately, or don't take the time to manually input an
address.
 
Which is not to say that his other points are not well taken.  The medium
often overwhelms the museum message.
 
--bayla