sitemap.xml location

Base URL of my site is http://boxbrosla.com/boxtest
There is no file 'http://boxbrosla.com/boxtest/sitemap.xml', when I go to that URL, I see the attached file 'sitemap.txt'
XML Sitemap is creating a complete sitemap at
'http://boxbrosla.com/boxtest/sites/default/files/xmlsitemap/40cd750bba98...' (attached as '1.txt')
is that correct?
Which file is the module submitting to search engines?
is this a user error?
a site issue ?
a bug?

Thanks,
Joe