You can use the conversations feature to group messages with the same subject line together in your inbox. You can:
Emails in a conversation view look much like other emails in your inbox. For each conversation, you’ll see:
Heads up: You won’t be able to sort email by sender or subject when you use Conversations view.
When you open a conversation, the newest email expands at the bottom of the thread. To open:
At the bottom of the conversation, choose from these options:
Don’t want to use the conversation view? Turn it off.
From your webmail inbox: