Microsoft Enables Feature That Blocks Reply-All Emails

Microsoft has introduced a new "Reply All Storm Protection" feature in Office 365. This email protection feature is intended to detect and stop "reply-all email storms,” which happen when a large group of people use the reply-all option in mass emails and trigger a flood of messages. Email storms are disruptive to company operations because they increase server activity and may cause servers to slow down or even crash. Microsoft said that the feature is designed to help large companies, which tend to have high email activity. The feature was first announced in 2019 but was made available only in May 2020. The feature automatically activates if 10 “reply all” messages are sent to more than 5,000 recipients on a company’s email server within an hour. When this happens, succeeding replies to an email thread will be blocked for four hours. According to Microsoft, a couple of internal incidents served as inspiration for creating the feature. The company has experienced two instances of “reply-all email storms,” one in January 2019 and another in March 2020. Over 52,000 employees were involved in these incidents, which disrupted internal servers for hours. Microsoft said that moving forward, it still wants to make improvements to the feature, such as adjusting it to be suitable for smaller companies. The company also plans to add controls for customizing email storm detection limits, as well as real-time notifications that alert administrators when email storms are starting. These notifications can help administrators monitor the status of email servers to prevent them from slowing down or crashing.