MicrosoftPreview user agent, IP ranges and robots.txt

Microsoft Bing operates MicrosoftPreview, which generates page snapshots for Microsoft products in desktop and mobile variants. Bing does not document a robots.txt token for it or state whether it honors robots.txt. Bing documents no verification method for MicrosoftPreview specifically; its generic guidance for all Bing crawlers covers the Verify Bingbot tool, reverse DNS to search.msn.com and the bingbot.json range file.

The desktop variant appears in logs as a Chrome-like User-Agent with MicrosoftPreview/2.0 and a link to aka.ms/MicrosoftPreview; the mobile variant uses an Android Nexus 5X Chrome User-Agent carrying the same token. The aka.ms link redirects to the Bing help article that lists its crawlers. Bing says the bot generates page snapshots for Microsoft products, but does not say which products display them or how often a page is fetched.

Bing does not document a robots.txt token for MicrosoftPreview and does not state whether it reads robots.txt at all, so the effect of a Disallow rule is undocumented. Bing publishes no IP range list specific to this bot and no reverse DNS suffix for it. The only verification guidance is the generic statement for all Bing crawlers, which names the Verify Bingbot tool, reverse DNS to search.msn.com and the bingbot.json file. Blocking the bot stops the page snapshots Bing describes; the documentation does not say what losing those snapshots changes in any Microsoft product. The registry files it as social-preview as the closest category, a term Bing does not use.

Operator note. The mobile user agent is Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/W.X.Y.Z Mobile Safari/537.36 (compatible; MicrosoftPreview/2.0; +https://aka.ms/MicrosoftPreview). The https://aka.ms/MicrosoftPreview link in the user agent redirects to the Bing crawlers help article. The documentation does not state which Microsoft products use it.