Liya, Jatheon's AI Chat Assistant, needs to be enabled on the Client level in order for you to see the option in the Search Results. 

At the moment, it's possible to chat with a single/multiple email attachments and with a social attachment (single). 

To do so, perform either the Email or Social search and get the results that have the textual attachments. 

Email Search 

To chat with a Single attachment, locate the blue AI icon (right next to the Preview and Download links).

To chat with Multiple attachments, locate the AI icon (right next to the Attachments label).

Once you click on it, you will get an option to select the text attachments you want to chat with:

You can Select All attachments or just the specific ones by turning the appropriate switch to ON. 

Social Search 

To chat with a Single attachment, locate the blue AI icon (before the file name in the social thread).

Click the AI icon and a small window will pop up where you can type in your questions.

Type your question in the Type a message input field. You can also use the Summarize file option. If you’ve already started conversations, you’ll see an All Chats button in the top-right corner.

Clicking it will open a list of all your previous chats. From there, you can search through past conversations, reopen any chat to continue where you left off, rename a chat by clicking the edit icon and delete a chat by clicking the bin icon.

Once you get the answer to your question, you can give it a thumbs up/down and copy it to the clipboard: