RVS-4000 and Gmail error: 501 5.5.4 Unrecognized parameter

Question

Hi,
My domain's MX record points to my RVS4000 router, which sends mail to our Exchange server.  We get a ton of mail everyday, but some mail never makes it to the Exchange server.
If I send a simple gmail To:  Joe  He'll get the email just fine.
If I send a simple gmail To:  Joe, Sally I will get the followiing error message:
Delivery to the following recipient failed permanently:
[email protected]
Technical details of permanent failure:
Google tried to
deliver your message, but it was rejected by the recipient domain. We recommend
contacting the other email provider for further information about the cause of
this error. The error that the other server returned was: 501 501 5.5.4 Unrecognized
parameter (state 15).
The email is not logged in Exchange or the spam software.
Some international email never arrives.
Is there a setting in the router that could be kicking out some of our email?
Thanks for your time.
Bruce

Answer 1

Thanks for your reply.
If all VPN routers from Linksys limited themselves to Class C addresses, why my configuration was accepeted?
Remote: 192.168.0.0 (255.255.0.0) => Class A?
Local: IP only 192.168.5.0
but not Local: 192.168.5.0; 255.255.255.0
Anyway I shall inquire the headquarter whether they can adjust their IP ranges "192.168.0.0; 255.255.0.0" to such as "192.168.2.0; 255.255.255.0"
thank you.
go4ecs