We have a GroupWise API gateway to connect to an Exchange 2003 system
using Microsoft's GroupWise and Calendar Connectors.

It seems to work ok.

Would it be possible to just use Calendar Connector so calendar
information and busy searches take place?

I think the GroupWise Connector will have to do the Address book so I
will need that also.

Main Question:

Is it possible to have emails diverted to an SMTP gateway (i.e. the
GWIA), instead of going through the API link?

And also, can something similar be done on the Exchange side?

It would mean names & email addresses will have to be represented on
both side as proper external email addresses.