We have an Exchange 2007 server and Outlook 2013 clients running on our Server 2008 / Windows 7 network.
All internet access is routed externally through a remote proxy server (for filtering, control, reporting etc).
When looking at the usage reports for traffic going through this external proxy server, I am often seeing high usage for various users, and the urls reported as being visited are 'mail.<our domain>.com' and 'autodiscover.<our domain>.com'
It's not always for the same users, and it's not happening all the time.
We do have the 'Microsoft Exchange Proxy Settings' in Outlook set on all PCs to use 'mail.<our domain>.com' but my understanding was that this would only be used if a local connection was not available - we set it up through GP so that any laptops will connect when off-site.
Any idea why Outlook is sending traffic externally (but only some of the time) to connect to the internal Exchange server?