Microsoft is rolling out a new reply-all protection feature for Office 365 and exchange online. It’s designed to prevent email storms (reply allpocalypse).

The new block feature will mostly benefit large organizations. It is initially being rolled out to detect 10 reply-all emails to over 5,000 recipients within 60 minutes.

Microsoft had its own infamous incident back in 1997. Around 25,000 people were on a distribution list and kept replying to the thread, generating 15,000,000,000 emails and 195 gigabytes of data.

Microsoft still suffers from reply-all email storms. Last year a GitHub notification triggered an email storm for thousands of Microsoft employees.