Table of Contents
Email Protocols : SMTP, MIME, POP & IMAP
‘Email’ means different things to different people
A Typical Mail Environment
PPT Slide
How Email Really Works
SMTP looks exactly like this
The Commands are Few and Specific
SMTP Reply Codes
Reply Codes Contain a Lot of Information
Most Common Reply Codes
RFC821 Defines all the Reply Codes
How to Forge Email
... and the resultant raw mail
Using VRFY/EXPN
Beware of vrfy on some mailers!
SMTP Extensions (EHLO)
An EHLO with Extensions
EHLO with an Old Mailer
Defined SMTP Extensions
SMTP Protocol Key Concepts
PPT Slide
A Typical Mail Message
A Typical Mail Message (continued)
Some Headers are More Important than Others
Anatomy of a Mail Message
Originator Headers: who it comes from
Originator Headers: who sent it on to you
Originator Headers: best reply address
Date Header is Required
Recipient Headers
The Crucial Received Header
Received Lines are Key to What’s Going On
Received Headers Show You the Path
Hop by Hop You Can Follow Each Email Message
Received Line Information
Received Line IP Address Authentication
The Crucial Message-ID Field
Received Headers often contain the Message-ID
Mail Messages Can Get Repeated Several Ways
Header Usage by Mailing Lists
Headers Key Concepts
MIME Multipurpose Internet Mail Extensions
MIME What is it?
MIME Does Two Main Things
How MIME Works
MIME adds new headers
New MIME headers
A sample message with binary attachment
The same boundary marker separates each section
The Content-Type Header
A Minimal MIME Message
Content-Type: Application
Content-type: Multipart
Multipart Messages Can Be Nested
Encoding Schemes are Defined
A Common Sight
MIME Handles Other Character Sets
MIME and Non-capable Mailers?
MIME User Agents
Best Way to Keep on Top of MIME is With the FAQ
MIME RFCs
... and more MIME RFCs ...
Client / Server Email POP and IMAP
Client/Server Email Follows 3 Main Models
POP and IMAP only get the mail
POP - Post Office Protocol
POP is very simple
POP has no security
IMAP Has Everything POP Doesn’t
In IMAP the Client is King
IMAP Has Stronger Authentication
The INBOX
Use EXAMINE for Debugging
Header Details Can be Seen
See What Folders Are Available
Rummage around in one...
And How To Get Out ...
IMAP Is Everything Needed
Configuring IMAP Service
IMAP Goes Beyond POP
PPT Slide
RFCs of Interest Just a Sample
More Fun RFCs
A Good Place to Get RFCs
Newsgroups of Interest
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