This article explains how to view your Outlook email messages by grouping conversation threads, so you don't have to search for all the messages that belong to a conversation. Instructions apply to Outlook 2019, 2016, 2013, 2010; and Outlook for Microsoft 365.

Outlook collects messages into a conversation spanning multiple days and folders and then displays them all together.

Start Outlook and go to the View tab.

In the Messages group, select Show as Conversations.