How to achieve email chain while sending a correspondence .

Ex: Customer sent an email which got attached to the case , now while replying to the customer the business wants to reply on the same email which the user sent , so that the customer will understand that he has received the reply for the mail which he sent previously.

Is there a way we can achieve this ? In my case , I have the eml files attached to the case . The eml files contains the email conversation between business and users . Now while sending a correspondence to the customer the business wants to reply on top of one of the eml file such that the email correspondence will include the respective contents of the eml file .

***Edited by Moderator Marissa to update Content Type from Discussion to Question***