The Reply by Chat feature allows you (and your contacts) to converse about an email message that you have sent or received, in real time. An added bonus is that if you have Gmail saving your chat history, the chat will be nested in with the rest of the conversation generated by the message.
1. Go to Gmail and log into your account.
2. Open the desired message.
3. Check to see if the contact is online and available.
4. Click the Reply by chat link at the bottom of the message (next to the Reply and Forward links).
5. A chat window will open. You will see the email message’s subject displayed. Begin chatting.
6. When the conversation is finished, close the chat window.
7. After a few seconds, go back to the email message and you will see the chat session included in the conversation. You can reply to it by email or start a new chat session.