Read the case study given below and answer the following questions

Mr. Mohammad, an accountant, works in an IT firm and due to the pandemic, has been asked to work from home. He has set up his online office at his home. He has purchased a laptop, web camera and other accessories. Now he has started working from home and performs his various duties online.

Mr. Mohammad sends an email to Harish requesting him to prepare the balance sheet. Which network protocol is involved during this email communication?