Is it possible to stop the High Sierra Mail app from grouping messages? I recently upgraded to a 13-inch MacBook Pro (2017 model) and installed macOS High Sierra version 10.13.2.  The new Mail app is grouping e-mails into "conversations", which has the net effect of making e-mails from my clients disappear under my replies.  I use Google mail (on the web),  the Apple Mail app on my MacBook, and the Mail app on my iPhone 6S.  My goal is to have all three of these apps simply display the e-mails in the order that they were sent and/or received.  I don't want some "helpful" feature on one platform adding to the overall cognitive burden.

The problem seems to have started with the last set of upgrades.  Does anyone know how it can be addressed, short of switching to Android?
Go to View and disable Organize by Conversation.