In our continuing efforts to provide great value to our publishers, the Bing Engineering team is constantly testing new features to improve crawl efficiency. Such experiments are vital to our ability to innovate and improve our end user and publisher experience.
Due to an upcoming experiment, a few sites may encounter an intermittent increase (anywhere from 5% to 25%) in crawl requests from MSNBot over the next month (specifically from August 25th through end of September). If you see an increased crawl rate on your site and want to throttle it down, please contact bwmc@microsoft.com as soon as possible, and we will address your concerns. Thanks for your understanding as we try to improve Bing for all of us.
— Sasi Parthasarathy, Senior Program Manager, Bing Engineering