iPhone Mail can also collect all messages to the same subject — and sort them chronologically, of course, but separately. It lets you act on the bunch, too, filing an entire thread, for example.
(Unfortunately, iPhone Mail only threads messages from the current folder; it does not include other folders, say your sent mail.)
Read Emails in Threads with iPhone Mail
To have iPhone Mail group messages with the same subject from the current folder:
- Go to your iPhone or iPod touch's Home screen.
- Open Settings.
- Select Mail, Contacts, Calendars.
- Make sure Organize By Thread is ON.
(Updated October 2011)