Estimate how many times the message changed hands (between sender and SMTP server, between SMTP servers, between SMTP and mailbox server)

List at least 3 reasons why this email was not really sent by the president? Assume youre sending an email to the professor. List at least two (technical/semi-technical) ways you can help the professor to ensure it is indeed from you and not forged?

Received: by 2002:05:6830:1253:0:0:0:0 with SMTP id s19csp27728otp; Thu, 6 Feb 2020 17:15:10 -0800 (PST) X-Google-Smtp-Source: APXvYqzbrb6acgnkFQbwx50/eY2UbOogdOfE5Q/wgxloa5BEUu9WbxrpfwmUJUVgvmPY1+eCcE/ X-Received: by 2002:a67:f4d2:: with SMTP id 518mr3533191vsn.15.1581038110361; Thu, 06 Feb 2020 17:15:10 -0800 (PST) Return-Path: Received: from cheetah.cs.fiu.edu (cheetah.cs.fiu.edu. [2001:468:701:4002:5c15:0:130:107]) by mx.google.com with ESMTP id x16si101247vsf.127.2020.02.06.17.15.10 for ; Thu, 06 Feb 2020 17:15:10 -0800 (PST) Received: by cheetah.cs.fiu.edu (Postfix) id 22D53233B6; Thu, 6 Feb 2020 20:15:10 -0500 (EST) Delivered-To: aa@cs.fiu.edu Received: from foobar.com (afanasyev-laptop-dock.cs.fiu.edu [131.94.145.16]) by cheetah.cs.fiu.edu (Postfix) with ESMTP id AAE6923DA6 for ; Thu, 6 Feb 2020 20:13:18 -0500 (EST) From: The President To: Prof. Alex Afanasyev Subject: Invitation to the white house Message-Id: Date: Thu, 6 Feb 2020 20:13:18 -0500 (EST) Dear Prof. Alex, I would like to invite you to visit the White House at your earlier convenience, as we urgently need your covfefe to solve the world crisis. Sincerely, The President of the United States of America Received: by 2002:05:6830:1253:0:0:0:0 with SMTP id s19csp27728otp; Thu, 6 Feb 2020 17:15:10 -0800 (PST) X-Google-Smtp-Source: APXvYqzbrb6acgnkFQbwx50/eY2UbOogdOfE5Q/wgxloa5BEUu9WbxrpfwmUJUVgvmPY1+eCcE/ X-Received: by 2002:a67:f4d2:: with SMTP id 518mr3533191vsn.15.1581038110361; Thu, 06 Feb 2020 17:15:10 -0800 (PST) Return-Path: Received: from cheetah.cs.fiu.edu (cheetah.cs.fiu.edu. [2001:468:701:4002:5c15:0:130:107]) by mx.google.com with ESMTP id x16si101247vsf.127.2020.02.06.17.15.10 for ; Thu, 06 Feb 2020 17:15:10 -0800 (PST) Received: by cheetah.cs.fiu.edu (Postfix) id 22D53233B6; Thu, 6 Feb 2020 20:15:10 -0500 (EST) Delivered-To: aa@cs.fiu.edu Received: from foobar.com (afanasyev-laptop-dock.cs.fiu.edu [131.94.145.16]) by cheetah.cs.fiu.edu (Postfix) with ESMTP id AAE6923DA6 for ; Thu, 6 Feb 2020 20:13:18 -0500 (EST) From: The President To: Prof. Alex Afanasyev Subject: Invitation to the white house Message-Id: Date: Thu, 6 Feb 2020 20:13:18 -0500 (EST) Dear Prof. Alex, I would like to invite you to visit the White House at your earlier convenience, as we urgently need your covfefe to solve the world crisis. Sincerely, The President of the United States of America