Reply-All Mail Storm protection now rolling out to Microsoft Office 365 and Exchange Online customers

Back in January 2019, as many as 11,543 Microsoft employees fell victim to the reply-all e-mail apocalypse, which is popularly known as Reply-all Mail Storm. Twelve months later in December 2019, Microsoft announced that they were working on a feature which would prevent future storms for Office 365 customers.

For those unaware, an email storm is a sudden spike of “reply all” messages on an email distribution list. It can start when even one member of the distribution list replies to the entire list at the same time.

“When a Reply-All mail storm happens in your organization it can disrupt business continuity and even cause unexpected throttling of your organization’s mail flow within Office 365,” Microsoft stated.

“While Exchange Online has several features designed to help prevent Reply-All storms (e.g. Distribution List (DL) allowed sender lists and recipient limits) that reduce the severity and impact of reply-all storms, they can still happen, especially if the DLs haven’t been locked down tightly.”

“The new Reply-All Storm Protection planned to arrive in Exchange Online during Q3 2020 works by detecting when Reply-All storms happen or are likely to happen and automatically block the involved users from replying to each other for a limited amount of time, “Bleeping Computer reported.

In the end, it did not take that long, and a few months early, Microsoft has started rolling out the feature to their cloud customers.

In its first iteration, it is tuned to detect 10 reply-all emails to over 5,000 recipients within 60 minutes.

“Over time, as we gather usage telemetry and customer feedback, we expect to tweak, fine-tune, and enhance the Reply All Storm Protection feature to make it even more valuable to a broader range of Office 365 customers,” notes Microsoft’s Exchange transport team.

“The temporary block will be active for several hours, usually enough time to dampen end-user enthusiasm to reply to the thread, and thus curtail the storm before it gets started or before it gains much momentum,” the development team noted.

Read more about the feature at Microsoft here.

Via The Verge