smtp realying

What is the best way to test for smtp authentication, relay etc.If
evolution was set up to connect to @domain.name.com with a popusername
and password and smtp was setup to connect to the@domain.name.com smtp
server. Once they were authenticated for popcould they then send smtp
messages from another program not evolutionthis being a virus of sorts
that is now trying to latch on to theconnnection created with the pop
authentication.


Jim