A thread of email messages on a mobile phone works the same way as it does in a web or desktop email application. In most cases, grouping emails into a thread is the default method, but you can usually edit your email preferences if you prefer to view your messages individually. In this guide, we'll show you how to manage threads on iOS, Android, and Windows Mobile devices.
Outlook Tips and Tricks to Take Control of Your Inbox
The built-in Mail application on Apple iOS has several settings that control email threading. Email threading is enabled by default.
Go to Settings and select Mail.
Scroll down to Threading.