I had recently setup a Cisco ASA 5510 for a remote location that has it's own Exchange server.
Through the ASA I setup VPN connectivity. The users use Cisco VPN client to connect to the network.
When the user works from home and tries to send email they get these as kick backs.
The destination server for this recipient could not be found in Domain Name Service (DNS). Please verify the email address and retry. If that fails, contact your administrator. <exchangeserver.domain.local #5.4.0>
While inside the office the email works fine.
The users had used a Windows VPN session in the past and that worked fine. So it's after we setup VPN through the ASA did this problem start happening.