Outlook 2000 recipients cannot open digitally signed email

[Glen]

I'm sure there is a fix for this somewhere, but the
knowledgebase can't seem to come up with a resolution to
my problem other than removing my digital signature.

I am using Office XP/Outlook 2002
Sending a digitally signed message through an Exchange
Server, the recipient using Outlook 2000 cannot open my
email. Other users of Outlook 2002 can open the document
and forward it to that user with no problem.

Short of removing my digital signature or upgrading the
recipient to Outlook 2002 is there a fix for this problem?