saving hashtable

hello everyone.

My problem is as follows :
my application keeps a hashtable with Outlook.MailItem objects.
I need to save and load this hashtable (with those objects inside) when
starting and terminating the
application.

I can't "serialize" them because Outlook.MailItem objects do not implement
the Iserializable interface.

so how do I go about saving and loading the hastable with the objects ??

Thanks
Inon