In a recent statement on Twitter, Microsoft stated that it is investigating an Office 365 issue that has led to legitimate emails from multiple domains, including Google and LinkedIn, being marked as malicious and quarantined.
According to Microsoft, the problem stems from an inadvertent blocking of valid and healthy domains, which resulted in legitimate e-mails being quarantined.
Microsoft is in the process of solving all problems.
In a comment in the Microsoft 365 Admin Centre, Microsoft explained that users are having several problems with the email flow and the Microsoft Defender Portal.
By 6:38 PM on Monday, Microsoft had solved some of the issues.
They tweeted: “We’ve ran commands to unblock the URLs, which will mitigate impact for all new email messages and links within email messages. We’re working to release the email messages that were quarantined, as well as investigating options to restore the health of the Microsoft Defender portal.”
For more information, read the original story in Bleeping Computer.