Exchange ’98 and Linux’ sendmail

– on a linux box, we have a custom email management application that creates files (based on user input via a gui) that sendmail can understand and dispatch (like mail/merge). this is typically used to send out bulk email
– we need to update these files that are created such that they can be sent to an Exchange ’98 server (instead of linux’ sendmail) which would then dispatch the emails
– i am looking for suggestions/tips; better yet, if there is anything out there that would make this as painless to do as possible.

Thanks in advance.