Groupwise 5.2 to Exchange 2000

We are migrating from Groupwise 5.2 on a Novell 4.11 server to Exchange 2000 on a windows 2000 server. We are able to communicate between the two via an API gateway on the groupwise server. We even migrated two test users over and everything went smooth. BUT the problem comes in when we add the exchange users to an already existing groupwise distribution list. When an e-mail is sent out to that group with an attachment the attachment comes out blank on the groupwise side but is fine on the exchange side. HELP!!!! Any ideas???