Duplicate Mail when cc Exchange

Greetings:

I have an issue with outgoing interenet mail that I cannot resolve.

When a user sends a message to an internet mail address and there is an in-house user cc'd, the internet mail address receives two copies of the message.

Although I've analyzed both message headers and found slight differences, there is nothing that stands out as the cause.

I do believe the trigger is happening between the Exchange 2000 server, (no on the internet), and the gateway mail server. (the connector in Exchange). The mail actually leaves the SMTP Internet server twice.

Any clues? Where should I look?

Thanks and warm regards,

Rick Forsythe
Systems Administrator