Message errors

I am using cc:Mail 8.2 (no jokes please, I inherited it and am in the process of slowly seeing it migrated to Exchange) and I’m trying to send mail to a state government address “username@sov.state.va.us” and I keep getting an error message that contains “The following addresses had transient errors” and “Deferred: sov.state.va.us.: No route to host”. I can ping the address with no problem and I can send mail to the person through my Yahoo account with no problem. Any ideas??? I’m stumped!