Kurose and Ross Edition 6 Exercise 2 Question P13 (Page No 174)

Question

What is the difference between MAIL FROM: in SMTP and From: in the
mail message itself?

Answer 1

The MAIL FROM: in SMTP is a message from SMTP client that identifies the sender of the mail message to the SMTP server. The From: on the mail message itself is NOT SMTP message, but rather is just a line in the body of the mail message.