Why am I unable to send or receive Exchange in Outlook without pressing the send/receive button?
Sometimes Outlook can go into an offline mode. To see if Outlook is in an offline mode see if File->Work Offline is checked. If it is check select the File->Work Offline menue item to uncheck it. Another possible solution is that Outlook is not set to send automatically; to fix this put a check in the "Tools->Options->Mail Setup->Send immediately when connected" box.