What are conversations?
After you begin using your school Apps mail account, you will notice in your inbox messages a list of contacts and a parenthesis number.
Apps mail groups all replies with their original message, to create a single conversation or thread. For example, lets say you send out an email about lesson plans to a group of teachers. In other email systems, the teachers' responses would appear individually as separate messages in your inbox, forcing you to wade through all your mail to see what people have said in their replies. In your Apps mail account, all messages related to the original email subject are displayed on one screen, in order, making it easier to understand the context of a message -- or to follow the conversation.
The number in the parenthesis corresponds with how many messages (or replies) are in the conversation.
When you open one message in a conversation, all of your related messages and replies will be stacked neatly on top of each other, like a deck of cards. Each sender has a different color avatar assigned to his or her name if they do not have a picture in their profile. Check to the To: and CC: fields to see if the message was sent just to you or to the entire group.
We call this Conversation View. In Conversation View, each new message is stacked on top of the ones that arrived before it, so that the newest message is always the one you see first.
To see all the messages in a conversation, just click the Expand All icon next to the printer icon. The most recent conversation will be at the bottom of the screen.
To see a single message within the conversation, click on it, and it will expand. You can click again to collapse back into the "deck" of the conversation.
Reference What are conversations