For some reason Outlook 2007, unlike Outlook 2003, requires that a network gateway
is set before it will connect to your Exchange server. I really wonder whether this
is a bug or not, it seems a bizarre requirement when most Exchange servers will be
on the local network. I would have thought that most companies would prefer to implement
a proxy server and not define a gateway. In fact, a workaround for this problem is
to set the http proxy settings within the Account Settings -> Change -> More
Settings -> Connection Tab:

If you enter your Outlook Web Access URL in this section then you can connect without
a gateway being set. This is obviously not a great solution, it would be nice if it
‘just worked’ like Outlook 2003 always did. This is especially true for corporate
network deployments. I am still left wondering whether this is a bug or not, I really
can’t understand how it would be a ’security feature’.