Outlook Prompting for Credentials

There are many reasons why outlook might prompt for credentials. However, one of the reasons that I often forget is when outlook tries to access an internal address or server via a web proxy, i.e. it does not know to bypass the web proxy when looking for the address or server in question.

Ensure all servers (including aliases) that Outlook should connect with internally are excluded in your web proxy configuration.

For other potential causes/fixes,  Ilan Lanz (Ilantz) has created a great troubleshooting list here.

References:
http://ilantz.com/2011/02/08/authentication-pop-ups-and-annoyances-with-exchange-2007-2010-and-outlook-anywhere/

Use proxy.pac to Auto Configure Proxy Settings

Proxy.pac files are great. They'll configure your proxy settings when you're on the protected network, but leave your system unaffected if you take it offsite to a network that does not require or use a proxy server.

Before I even begin to create something of my own I must recognise the following sources:
http://marckean.wordpress.com/2010/02/09/setting-up-proxy-pac-files-in-iis7-for-proxy-use/
http://nscsysop.hypermart.net/setproxy.html
http://nscsysop.hypermart.net/proxypac.html
http://technet.microsoft.com/en-us/library/dd361950.aspx

These sources are all you really need to get going, but I may put some more info up here more specific to the things I do with proxy.pac files.