As a result of a recent security threat against ALI customers, we have re-introduced several paranoid security settings, causing some customers of other ISPs problems collecting mail from our servers.
If your anti-virus program is set to scan E-mail as it is collected, it is a good idea to turn this option off. This might sound like a bad idea, as E-mail is where most of the virii come from. The problem is, this "feature" usually breaks after a while.