"unable to relay to the destination mail address"
this is probably due to your smtp restrictions are not allowing relay to any non-local destination.
To setup an email server that relays mail anywhere it needs to only relay for local users, which is the default. Your ssl connection should be seen as a local connection therefore the default settings would allow you to send anywhere.
You do not want port 25 to allow relay, only the internal connection. Otherwise you would be running an open relay.
You can have a look at this and maybe get some idea about your setup.
http://www.linuxquestions.org/questi...ticle&artid=50
In the discussion area of that post there is also some updated ideas that may be useful.