Mail\SMTP routing problem

I have the following scenario:

Server A is an extranet server on our DMZ

Server B is an extranet hub server on our LAN

I would like to route email from A to B then onto a mailsweeper server via SMTP. Server A cannot connect to the mailsweeper server, so all mail must go via Server B. The emails are addressed to users who exist in a Notes domain which is adjacent to the Notes domain that the extranet servers belong to. Unfortunately, because of security reasons we do not want to enable Notes mail routing between the 2 domains.

I’ve tried various combinations of connection, configuration and domain documents but have not been able to get this working. Does anyone have any suggestions?

Many Thanks in advance,

Phil