Some time after I released the Sitemap Generator Umbraco package, I
realized that some search engines and SEO tools only looked for a
file called "sitemap.xml".
My package only renders a "sitemap.aspx" file, so this had to be
fixed. Rather than developing a control that changes the file
extension of the .aspx file, I looked into URL Rewriting.
Note: This tutorial is originally designed
for websites with the sitemap.aspx file in the root. I.e. /sitemap.aspx
. You can also use this tutorial with other files or
extensions.
First, make sure you have installed the URL Rewrite 2.0 extension for IIS
7.x.
Then go to your site in the IIS Manager and click on "URL
Rewrite".

Then click "Add Rule(s)" in the upper right corner and select
"Blank Rule".

Now fill in the information in the picture below:
Pattern: ^(.*)sitemap.xml
Rewrite Url: {R:1}sitemap.aspx

Now you can test it by navigating
to http://your.url/sitemap.xml.
See it in action here: /sitemap.xml