Plugger and spaces (%20) in URL attached documents

I'm using Mozilla 1.1, Plugger, and the Outlook Web Access for my Linux
users to connect to an Exchange server. I've modified /etc/pluggerrc to
use OpenOffice for opening MS Excel documents. File attachments show up
as links. If the attachment has spaces in the name, then I get errors
when clicking the link.

The OpenOffice splash screen pops up and then a dialog box says:

Error loading document file:///tmp/plugtmp/PHONE%20DIRECTORY-%20March.xls:
/tmp/plugtmp/PHONE DIRECTORY- March.xls does not exist.

/tmp/plugtmp has this file:

PHONE%20DIRECTORY-%20March.xls

Does anyone have any suggestions on how to handle spaces in URL
attachments with Plugger and/or OpenOffice?
Thanks,
~Matt