Microsoft Bing has said it's removing the facility to submit anonymous sitemap submissions, which it says, "was often subject to misuse by spammers.

It goes on to say that it recommends having sitemaps with all relevant URLs hosted on the site, and that the methods to use are:-

robots.txt: Add a reference to your sitemap in the robots.txt file located at the root of the host to inform all search engines.

Sitemap: http://www.example.org/sitemap.xml

Bing Webmaster Tools: Alternatively, you can submit your sitemaps in Bing Webmaster Tools [bing.com...]

It also goes on to encourage webmasters to "adopt [indexnow.org...] to inform Bing and other search engines real time of latest content changes on their websites."

[blogs.bing.com...]