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This is a directory of program listings from Chapter 13 of the book:
- Foundations of Python Network Programming
-
Third Edition, October 2014
by Brandon Rhodes and John Goerzen
You can learn more about the book by visiting the root of this GitHub source code repository.
These scripts were written for Python 3, but can also run successfully under Python 2. Simply use 3to2 to convert them to the older syntax.
The scripts in this chapter are best exercised inside the network
Playground where mail.example.com is
already set up and configured to receive incoming email. Once the
playground is running, ask for a prompt on the h1 host and visit the
chapter13 directory:
$ ./play.sh h1
# cd py3/chapter13
At the h1 machine’s prompt you can then experiment with sending
messages across the network. The simple.py script and the slightly
more advanced ehlo.py do their work silently, while debug.py asks
the Standard Library to show the communication that is going on at the
socket level.
$ python3 simple.py mail.example.com sender@example.com brandon@example.com
Message sent to 1 recipient
$ python3 ehlo.py mail.example.com sender@example.com brandon@example.com
Maximum message size is 10240000
Message sent to 1 recipient
$ python3 debug.py mail.example.com sender@example.com brandon@example.com
send: 'ehlo [172.17.0.10]\r\n'
reply: b'250-mail.example.com\r\n'
reply: b'250-PIPELINING\r\n'
reply: b'250-SIZE 10240000\r\n'
reply: b'250-VRFY\r\n'
reply: b'250-ETRN\r\n'
reply: b'250-STARTTLS\r\n'
reply: b'250-ENHANCEDSTATUSCODES\r\n'
reply: b'250-8BITMIME\r\n'
reply: b'250 DSN\r\n'
reply: retcode (250); Msg: b'mail.example.com\nPIPELINING\nSIZE 10240000\nVRFY\nETRN\nSTARTTLS\nENHANCEDSTATUSCODES\n8BITMIME\nDSN'
send: 'mail FROM:<sender@example.com> size=210\r\n'
reply: b'250 2.1.0 Ok\r\n'
reply: retcode (250); Msg: b'2.1.0 Ok'
send: 'rcpt TO:<brandon@example.com>\r\n'
reply: b'250 2.1.5 Ok\r\n'
reply: retcode (250); Msg: b'2.1.5 Ok'
send: 'data\r\n'
reply: b'354 End data with <CR><LF>.<CR><LF>\r\n'
reply: retcode (354); Msg: b'End data with <CR><LF>.<CR><LF>'
data: (354, b'End data with <CR><LF>.<CR><LF>')
send: b'To: brandon@example.com\r\nFrom: sender@example.com\r\nSubject: Test Message from simple.py\r\n\r\nHello,\r\n\r\nThis is a test message sent to you from the debug.py program\r\nin Foundations of Python Network Programming.\r\n.\r\n'
reply: b'250 2.0.0 Ok: queued as 98034261\r\n'
reply: retcode (250); Msg: b'2.0.0 Ok: queued as 98034261'
data: (250, b'2.0.0 Ok: queued as 98034261')
Message sent to 1 recipient
send: 'quit\r\n'
reply: b'221 2.0.0 Bye\r\n'
reply: retcode (221); Msg: b'2.0.0 Bye'
After connecting to the mail machine with the username brandon and
the password abc123 you can use the venerable mail command to see
that three new test messages are in your mailbox, thanks to the three
Python scripts that you just ran:
# ssh brandon@mail.example.com
brandon@mail.example.com's password: abc123
You have new mail.
$ mail
"/var/mail/brandon": 6 messages 6 new
>N 1 Administrator Tue Mar 25 17:14 9/345 Welcome to example.com!
N 2 Administrator Mon Apr 21 12:08 11/431 Introduction to e-mail
N 3 Test Sender Mon Apr 21 13:41 40/1135 Foundations of Python Net
N 4 sender@example.com Wed Oct 22 20:34 14/477 Test Message from simple.
N 5 sender@example.com Wed Oct 22 20:34 14/476 Test Message from simple.
N 6 sender@example.com Wed Oct 22 20:35 14/475 Test Message from simple.
? q
Held 6 messages in /var/mail/brandon
The login.py and tls.py scripts are for the more advanced cases
where an SMTP server requires authentication or TLS encryption —
situations for which the Playground SMTP server is not yet configured.