SMTP 'Send Mail' from one client to another client on diff box (HP0-1xx to RP0-1XX)

[Rick Sample]

Here is what we have:
Two clients on two different boxes both on 4.6C.
One is HR box (hp0 1XX) , the other is our business on R/3 (RP0 1xx)
Portals single signon 6.2 , which does not display Inbox Documents
(can't see messages vai Portals)
 
Most users live in the RP0 box to do their work. What management wants
is to
send all messages that currently route to HP client to route to the RP
client so
users do not have to constantly log into the HP box to get completion /
rejection messages.
 
What is the best way to route? SMTP? Or some other service?
Personally I suggested SMTP to GroupWise e-mail since the total monthly
messages are less that 500 a month
but that got shot down. Don't ask why...
 
TIA
Rick Sample
Graybar Inc.