*:96 Overheads. More about this course about Internet application protocols can be found at URL:

Transcription

1 3-1 *:96 Overheads Part 3a: introduction More about this course about Internet application protocols can be found at URL: Last update: 29 Jan 2005

2 Internet address format 3-2 "Paul K. Rarey" User friendly name address

3 Envelope, Content, Heading and Body 3-3 Subject: RE: Meetings Date: Fri, 12 Jan :34: From: "Mary Smith" To: "James Thorn" Heading We met, we parted, we met again. We did not know then, that what we had, was the best that our life good give. Body MAIL RCPT Envelope

4 3-4 Multiple Relaying because of Firewalls Firewall Gateway Firewall MTA close to the sender MTA close to the recipient Sender UA Recipient UA

5 Storage of Mail in MTAs 3-5 Storage in spool area Storage in separate mailbox for each recipient Sender mail UA MTA close to the sender SMTP SMTP MTA close to the recipient POP or IMAP Recipient mail UA

6 Split of Messages in MTAs 3-6 Sender mail client Message with two recipients MTA close to the sender Message with one recipient Message with one recipient MTA close to the first recipient MTA close to the second recipient Recipient mail client Recipient mail client

7 Saving Netload by Split in MTAs 3-7 MTA in Europe Message with two recipients Message with one recipient MTA in North America Recipient MTA Sender mail UA Message with two recipients Message with one recipient Recipient MTA

8 3-8 From and MAIL FROM for Mailing Lists Original sender MAIL FROM: RCPT TO: Envelope From: Henry Smith To: Flower lovers Heading Mailing list MAIL FROM: RCPT TO: Envelope From: Henry Smith To: Flower lovers Heading Final recipient

9 RCPT TO versus To after Split 3-9 Originator RCPT TO: RCPT TO: First MTA RCPT TO: RCPT TO: MTA for the first recipients MTA for the second recipients

10 Mail architecture and spooling 3-10 Picture from Comer: Internetworking with TCP/IP page 434

11 Mail aliasing and forwarding 3-11 SMTP SMTP SMTP SMTP POP, IMAP or File Access Picture from Comer: Internetworking with TCP/IP page 436

12 Forwarding with a MIME Message/rfc New message heading: Content-Type: message/rfc822 Original forwarded message heading and body

13 Forwarding with a MIME multipart message 3-13 New message heading Added text explaining why this message was forwarded Forwarded message as a body part of type message/rfc822

14 Resending and Forwarding 3-14 Original message Resent message Forwarded message Date: 14 Jan :35 From: Donald Duck To: Jacob Palme Date: 14 Jan :35 Resent-Date 14 Jan :35 From: Donald Duck Resent-From: Jacob Palme To: Jacob Palme Resent-To: Ducklovers Date: 14 Jan :35 From: Jacob Palme To: Ducklovers > Header and body of original message

15 Original message Mime forwarding variant 1 Date: 14 Jan :35 From: Donald Duck <dduck@northpole.foo> To: Jacob Palme <jpalme@dsv.su.se> Date: 14 Jan :35 From: Jacob Palme <jpalme@dsv.su.se> To: Ducklovers <dlovers@dsv.su.se> Content-Type: message/rfc822 Date: 14 Jan :35 From: Donald Duck <dduck@northpole.foo> To: Jacob Palme <jpalme@dsv.su.se> 3-15

16 Original message Mime forwarding variant 1 Date: 14 Jan :35 From: Donald Duck <dduck@northpole.foo> To: Jacob Palme <jpalme@dsv.su.se> Date: 14 Jan :35 From: Jacob Palme <jpalme@dsv.su.se> To: Ducklovers <dlovers@dsv.su.se> Content-Type: Multipart/mixed Content-Type: message/rfc822 Date: 14 Jan :35 From: Donald Duck <dduck@northpole.foo> To: Jacob Palme <jpalme@dsv.su.se> Content-Type: Text/plain Comment on forwarded message 3-16

17 Person A To: B ID: Text body Person B 3-17 To: A, B ID: 4711 Text body To: C ID: Person C To: B ID: Text body Text body

18 3-18 Methods of forwarding (a) Add new Resent-headers to the original message. (b) The forwarded message is made into a body part of type message/rfc822 in a new multipart message: (c) The text of the forwarded message is simply copied into the text of the new message. Which method is best if the forwarded message had a digital seal?

19 3-19 MAIL FROM (Envelope) versus From (Header) Original message Forwarded message RCPT MAIL Date: 14 Jan :35 From: Jacob Palme To: CMC mailing list RCPT MAIL Date: 14 Jan :35 From: Jacob Palme To: CMC mailing list