Fully functional SMTP mail server using grammar provided from HW1-HW3 as well as what is defined below. An example of the three way handshake added this HW is shown right under this text.

220 comp431fa20.cs.unc.edu
HELO comp431fa20b.cs.unc.edu
250 Hello comp431fa20b.cs.unc.edu pleased to meet you

220 Greeting :== 220 Random “greeting” text that includes the name of the server
HELO: == HELO
250 Response :== 250 Hello comp431fa20b.cs.unc.edu pleased to meet you

From Input :== From: reverse-path (with angle brackets)
To Input :== To: list of one or more forward paths (each with angle brackets)
Subject Input :== Subject: Text of the subject line formatted exactly as typed in by the user

Message Input: == Text of the message formatted exactly as typed in by the user.

Closing connection :==221 closing connection

Example:) Client running program on terminal == python ./Client.py comp431fa20.cs.unc.edu 17326
From:
[email protected]
To:
[email protected]
Subject:
How the heck are we going to grade HW4?!
Message:
TAs – How are we going to grade HW4? It’s going to require executing two programs for each
student on two separate machines and this is going to be difficult to automate!
.

(This is not shown to standard out, these messages are sent to the Server.py program via socket after 3-way handshake)
MAIL FROM: [email protected]
RCPT TO: [email protected]
RCPT TO: [email protected]
DATA
From: [email protected]
To: [email protected], [email protected]
Subject: Test message
This is a test.
.
QUIT

(This is not shown to standard out, these messages are sent to the Client.py program via socket after-3 way handshake)
250 Ok
250 Ok
250 Ok
354 Data ready end with './.'
221 comp431fa20.cs.unc.edu closing connection