maximum buffer size exceeded

[Daniel C. Bastos]

I'm dealing with an INBOX of size 252 MiB and I expect it to double on
my next mail downloads. I use VM under the GNU emacs. How can I increase
the buffer?

Ideally, I would finish my downloading; my mailbox will be about 530 MiB
and then I will compress it and save it as a backup. And then I can
delete mail. Any help?

On 

http://www.gnu.org/software/emacs/manual/html_node/emacs/Buffers.html#index-buffer-size_002c-maximum-1081

I read bad news: ``buffer's size cannot be larger than some maximum,
which is defined by the largest buffer position representable by the
Emacs integer data type. This is because Emacs tracks buffer positions
using that data type. For 32-bit machines, the largest buffer size is
256 megabytes.''

That's pretty much how large my INBOX is. Just thought of asking some
opinions. I suppose I will just have save my mail in three INBOXes.