I have two SharePoint Foundation environments (a test and production) that are near identical in configurations. When I look at incoming email settings in both environments, they are the same (IIS6 Manager SMTP Settings). In the first environment, I can set the incoming email settings in Central Admin to use automatic settings and the libraries pick up attachments in the drop folder fine. The second environment, when setup with the same automatic settings option, will not. If I change to advanced and put the default drop folder location (e.g. C:\inetpub\drop) it works fine. If I change back to automatic, it stops working.
Is there any reason why an environment would not work with automatic settings but would with advanced?