Scan to email via VPN blocked

Our Ricoh multi-function machine has been programmed for some time to send scans to our email via the corporate exchange server. Our IT staff recently replaced our old Cisco VPN routers with new SonicWall ones. Since they did that, however, our multi-function machine has been unable to send emails. We are able to access the exchange server just fine using our desktop and laptop computers.

I have run wireshark and can see the copier contact the exchange server and I see the exchange server respond but the communication from the exchange server suddenly cuts off and I see the copier send several ACK requests before giving up. No one in the copier or IT departments have been able to solve the problem.

I have even tried setting the multi-function up to send emails via an internet SMTP server. It has the exact same problem. Obviously the SonicWall router is blocking the SMTP traffic but it is not supposed to be and I can find nothing in it's settings to suggest why it is doing it. No email filtering is on and the VPN tunnel should not be blocking any traffic at all. I tried adding a rule to the firewall to allow all SMTP traffic but it made no difference.

Any help would be greatly appreciated!

~Rob