SMTP is a Simple Transport
The Notes Connector
does a nice job of synchronizing the directories. However, if
the Connector is also configured (as it is by default) to
conduct messaging, it becomes the sole transport for messages
between the two systems. This translates to a single point of
failure for messaging between the Notes and Exchange
environments. The typical Connector configuration is as
follows:
It is possible to
configure the Connector to perform directory synchronizations
without message routing, but the adjustment is kluge at best,
and support becomes an even greater issue. You also have to
live with some limitations, including the lack of replication
for group memberships.
By contrast, SMTP is a
great message transport in a heterogeneous environment. Major
software and service vendors, including Microsoft and Lotus/IBM
support SMTP. If we off-load the message transportation to SMTP,
we can get our systems to look more like the following diagram:
Using SMTP as our
message transport, we can potentially setup each server to route
mail independently, eliminating the single point of failure
created by using the Notes Connector.
The next step is to
create an internal SMTP routing system that will support the two
internal systems (Notes and Exchange). | 
