Bing's Frédéric Dubut said on Twitter that Bing does do proactive webmaster outreach. So if a site has a crawl issue that is negatively impacting search and the site, Bing may reach out via email.
Natasha Robinson asked Frédéric about this on Twitter asking " Is there a Bing Webmaster Outreach Co-ordinator at Bing that emails sites with the email address bwmor....@ microsoft?" Natasha wanted to make sure that this was not a scam email.
He responded "Hi Natasha - yes there is. When we receive negative user feedback and determine the root cause is a crawl issue, we reach out directly to webmasters to let them know."
Here are those tweets:
Hi Natasha - yes there is. When we receive negative user feedback and determine the root cause is a crawl issue, we reach out directly to webmasters to let them know. If these e-mails look like phishing maybe we should improve them - I'll pass the feedback to the crawl team.
— Frédéric Dubut (@CoperniX) December 9, 2019
Google does this as well.
Forum discussion at Twitter.