Hi,Your story is a little bit confusing because the scenario's you mention doesn't match with the examples.So I had a look at the examples you gave and here's a short explanation per example1) it can be that the receive connector with the anonymous authentication method doesn't match an IP of the internal client, in this case the other receive connector is used which requires authentication. If you will perform the same test from Outlook it will work.2) no explanation needed I think3) no explanation needed I think4) I think this is required because of the RFC821So when looking at the issue it looks like there is a missing helo/ehlo domain on the send connector. Please check the send connector and make sure it contains a correct