NewOutlook
Outlook: Notification when not responding to most recent message of email thread
Outlook for Windows and web will display a notification when users reply to an older message in a conversation thread rather than the most recent message, helping prevent accidental responses to outdated messages.
Microsoft's description
When replying to an email conversation and the message being replied to is not the latest in the conversation, Outlook for Windows and web will now display a notification indicating this. With this change, users can now be more confident that they are responding to the right message in an email conversation. #newoutlookforwindows