Here is my problem. I have set up an exchange server (2003) to eventually take responsability for all domain email but at the moment it opperates in as a "go between"
The previous people responsable had set up a "catch all" mailbox on one of their domains and also use a hosted exchange account for 2 of the members.
I have added a pop3 connector to download the email from the catchall and forward it to the exchange server and this is working ok. I have set up a smtp relay service so the server can send without going through the isp mail servers and that works ok.
Now the problem is if I change the MX record on the domain to point to the public address of our exchange server the hosted accounts will no longer function - although eventually this will be implemented. No when they send email the "from field" and reply address must be for that domain so I have set the primary email address as that domain name so all replys are then sent to the catchall mail box on the isp. The problem being is trying to send mail to the 2 users that have the hosted account "off site" as the exchange server will just trigger a NDR as it does have any details of those address for the domain. I cannot connect the 2 users to the internal exchange as only one exchange server is allowed. If I change the default domain email address to say "local" inseat of "com" for the internal users then in theory exchange will send all "com" messeges out. Is there a way to set the "from or reply to" headers or info in outbound mail to the "com" address? that way they can send email as normal and also the external users will also recieve email from the internal users. All email will eventually be handled by the exchange server but as they are linked to about 20 domains and have e-commerce on 3 domains it will take time to migrate the account and I need to enable external users to recieve the email sent by the internal users.