Microsoft has released patches for multiple different on-premises Microsoft Exchange Server zero-day vulnerabilities that are being exploited by a nation-state affiliated group. The vulnerabilities exist in on-premises Exchange Servers 2010, 2013, 2016, and 2019.  Exchange Online is not affected. We wanted to ensure you were aware of the situation and would ask that you help drive immediate remediation steps.  Specifically, to minimize or avoid impacts of this situation, Microsoft highly recommends that you take immediate action to apply the patches for any on-premises Exchange deployments you have or are managing for a customer or advise your customer of the steps they need