SMTP Routing

I have a strange problem hope you can help me out…

We have several server in our domain, some of them use a own Email SMTP. Now i have setup a test server i want that this server sends himself SMTP mails out so he dont forward smtp mails to a other server with a thirdparty smtp. It works fine if i have no connetions to servers how have a external smtp. If i add a conneciton for mailrouting he dont send smtp mails himself he starts to route those mails as well to the other server and from there the other server sends the mail to the internet. How can i forcre this test server to resolve the dns himself and sends the mail out ?

Even if i create a ajectant domain SMTP domain docuemnt and a smtp connection docuemnt hi sends the mail to other servers. The field SMTP used when sending messages outside of the local internet domain is enablet i have no idea why he sends the mail to other server if he have a connection doc to them.

hope you have some ideas