Microsoft has introduced in Exchange Online an automatic mechanism to handle “Reply All” storms that can paralyse corporate mail.
The problem
In large organisations it happens regularly: someone sends a communication to the entire company, an employee accidentally replies to all, and within minutes an avalanche of replies overloads the mail servers and clogs everyone’s inboxes.
Microsoft’s solution
Exchange Online now has a centralised checkpoint that analyses outgoing email traffic and, when it detects a mass reply exceeding certain thresholds, automatically quarantines the message.
Key features:
- Automatic detection of reply storms based on number of recipients and frequency
- Transparent quarantine — the sender receives a notification, not a generic error
- Customisation — IT administrators can configure thresholds and define specific rules to reject or block types of messages
- No impact on normal emails — the system only intervenes in cases of anomalies
For companies
This feature is particularly useful for SMEs with tens or hundreds of employees where a single “Reply All” mistake can cause significant disruption. Configuration is manageable from the Microsoft 365 administration portal at no additional cost.