Hidden Features of ASP.NET [closed]

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There are always features that would be useful in fringe scenarios, but for that very reason most people don't know them. I am asking for features that are not typically taught by the text books.

What are the ones that you know?

Solution 1:

While testing, you can have emails sent to a folder on your computer instead of an SMTP server. Put this in your web.config:

<system.net>
    <mailSettings>
        <smtp deliveryMethod="SpecifiedPickupDirectory">
            <specifiedPickupDirectory pickupDirectoryLocation="c:\Temp\" />
        </smtp>
    </mailSettings>
</system.net>

Solution 2:

If you place a file named app_offline.htm in the root of a web application directory, ASP.NET 2.0+ will shut-down the application and stop normal processing any new incoming requests for that application, showing only the contents of the app_offline.htm file for all new requests.

This is the quickest and easiest way to display your "Site Temporarily Unavailable" notice while re-deploying (or rolling back) changes to a Production server.

Also, as pointed out by marxidad, make sure you have at least 512 bytes of content within the file so IE6 will render it correctly.