Note: You can turn off conversation view so that your Inbox sorts and behaves as you wish without using the thread of a conversation as a variable.
Microsoft Outlook 2016 and Outlook 2019
To Turn on or off Conversations
- On the View tab, in the Messages group, select or clear the Show as Conversations check box
- Confirm your choice when prompted to apply the setting for this folder or all folders
Office 365 Exchange Online Webmail
- For each folder, click the Filter menu, point to Show as and select either Messages or Conversations
Mac Outlook 2016 and Mac Outlook 2019
- For each folder, click Organize on the ribbon then select or deselect the Conversations icon
macOS Apple Mail
- For each folder, click the View menu and select or deselect Show Related Messages