1. CIT 383: Administrative Scripting
Electronic Mail
CIT 383: Administrative Scripting

2. CIT 383: Administrative Scripting
Topics
MTAs
SMTP
Message Stores
POP and IMAP
CIT 383: Administrative Scripting

3. CIT 383: Administrative Scripting
MTAs
Mail Transport Agents use SMTP protocol
Receive mail from MUAs.
Route mail across internet.
Examples
sendmail
postfix
qmail
exim
MS Exchange
CIT 383: Administrative Scripting

4. CIT 383: Administrative Scripting
SMTP Example
220 brahms.nku.edu ESMTP Sendmail ; Wed, 12 Apr 2006
helo mydomain.com
250 brahms.nku.edu Hello mydomain.com, pleased to meet you
mail from:
Sender ok
rcpt to:
Recipient ok
data
354 Enter mail, end with "." on a line by itself
Subject: Test
From:
To:
This is a test. .
k3GIcr Message accepted for delivery
quit
brahms.nku.edu closing connection
CIT 383: Administrative Scripting

5. CIT 383: Administrative Scripting
SMTP Commands
HELO hostname
EHLO hostname
MAIL FROM: addr
RCPT TO: addr
VRFY addr
EXPN addr
DATA
QUIT
RSET
HELP
CIT 383: Administrative Scripting

6. CIT 383: Administrative Scripting
SMTP in Ruby
require 'net/smtp'
message = <<EOM
From: #{from}
To: #{to}
Subject: smtp test
This is a test message.
EOM
smtp = Net::SMTP.new(server, 25)
smtp.start do |smtp|
smtp.send_message(message, to, from)
end
CIT 383: Administrative Scripting

7. CIT 383: Administrative Scripting
Message Store
Communication
Receives data from MDA (mail.local, procmail)
Provides data to MAA (IMAP, POP, NFS, web)
Types of stores
Files (all messages for a user in one file)
Directories (directory per user)
Databases
CIT 383: Administrative Scripting

8. CIT 383: Administrative Scripting
POP and IMAP
POP: Post Office Protocol
Simple download protocol for offline reading.
IMAP: Internet Mail Access Protocol
Online and offline modes of reading.
Partial message fetch (headers, attachments, etc.)
Message state stored on server, not client.
Multiple mailbox and multiple client support.
CIT 383: Administrative Scripting

9. CIT 383: Administrative Scripting
POP3 Example
S: +OK POP3 server ready
C: APOP mrose c4c9334bac560ecc979e58001b3e22fb
S: +OK mrose's maildrop has 2 messages (320 octets)
C: STAT
S: +OK 2 320
C: LIST
S: +OK 2 messages (320 octets)
S: 1 120
S: 2 200
S: .
C: RETR 1
S: +OK 120 octets
S: <the POP3 server sends message 1>
C: DELE 1
S: +OK message 1 deleted
C: QUIT
S: +OK dewey POP3 server signing off (maildrop empty)
Example from
CIT 383: Administrative Scripting

10. CIT 383: Administrative Scripting
Accessing Mail in Ruby
Files (mbox format)
require ‘mailread’
mbox = Mail.new(fh)
POP
require ‘net/pop’
pop = Net::POP3.new(server)
pop.start(user, pass)
IMAP
require ‘net/imap’
imap = Net::IMAP.new(server)
imap.login(user, pass)
CIT 383: Administrative Scripting

11. CIT 383: Administrative Scripting
References
Michael Fitzgerald, Learning Ruby, O’Reilly,
David Flanagan and Yukihiro Matsumoto, The Ruby Programming Language, O’Reilly, 2008.
Hal Fulton, The Ruby Way, 2nd edition, Addison- Wesley, 2007.
Robert C. Martin, Clean Code, Prentice Hall,
Dave Thomas with Chad Fowler and Andy Hunt, Programming Ruby, 2nd edition, Pragmatic Programmers, 2005.
CIT 383: Administrative Scripting