SMTP service error 421

Hello,we’ve got some problems with our brand new domino 8.0.1 - server, especially with the smtp-service. Everytime we try to test the connection via “telnet 192.168.200.111 25” this message appears: “421 smtp.ourcompany.de SMTP service not available, closing transmission channel”

The needed firewall ports are open, three smtp-server-tasks are running (Status: control task, utility task, listen for connect request on tcp port 25).

The server is (of course) reachable, the “SMTPMaxSession” option is missing in the notes.ini.

I’ve got no idea how to fix the problem, and I’m a domino newbie too.

Can someone help me please?