how to archive messages on local computer?

[Virgil Simplaceanu]

Hello there!

I would like to copy my mail to a local disk (or even ZIP disk) and
then delete it from my INBOX in order to stay within the quota.
It was easy on the old MacMail ...
I cannot find any (at least simple) way of doing it with Mulberry, 
especially that I don't have my own and private computer, but depend on 
using a shared lab computer.
Regards,

Virgil Simplaceanu