We are having trouble with our Out Of Office reply not working. If you set the assistant to "out of the office", and set a message, it won't reply internally or externally. Funny enough, the administrator account works fine though.
The following has been checked.
setting under Global Settings >Internet Message Formats , And right click 'default' (in the right hand pane), Select Properties > Advanced
Tick the 'allow out of office responses' box