We recently went live with Exchange 2010 after finally dumping PSTs. We are using Scrollout's free service to filter our junk mail. We have a number of external offices all connected via a bunch of Watchguard VPN firewalls. Each of these locations have a Xerox multifunction machine that was originally emailing scans to our old ISPs address. All of our email accounts were there as well, and mail was POPped off.
We still have SMTP.ourcompany.ca pointing towards the ISPs address. Our MX record points towards Scrollout's gateway address. Our mail. A record points towards our exchange server's external IP (via the firewall of course).
If I have our Xerox machines setup to send mail to smtp.ourcompany.ca 25 they go through the ISP, and can send their scans to the outside world. They cannot send internally to the Exchange users though.
If I set the Xerox machines to send mail to mail.outcompany.ca 25 they go through our Exchange server, and can send scans internally. They cannot send their scans externally.
As a last note there is a device mailbox on the server called Scans@ourcompany.ca.
Can anybody recommend a solution that will allow me to somehow get the Xerox machines to send internally and externally? I've been tossing around ideas like authenticated forwarding and perhaps some different DNS records, but am pretty unsure how to proceed at this point.