dns is working just fine. there is no mx record for smtp.comcast.net. (dig smtp.comcast.net mx on linux). it shouldn't work after the ping, either.
comcast should have this record in their database: smtp.comcast.net. $TTL in mx smtp.comcast.net. i suffered the same problem when setting up my domain. the solution is probablly to add smtp.comcast.net in your ndb database. maybe upas should lookup the a/aaaa record if there's no mx record as a fallback. i'd be careful about doing that, though. - erik
