5. 6. 7. eMail

Question 1

Describe the process of Alice sending an eMail to Bob

Answer 1

Alice writes email on her email client
Email goes to SMTP client (or queue if offline)
Email goes to IMAP or POP server which figures out whether Bob exists
Bobs email agent fires up and communicates with POP to see if there is any mail

Question 2

Two Factors of complexity in eMail?

Answer 2

Recipient may not be connected to the internet.

An eMail moving from server to server represents a transfer of state.

Question 3

Email is asynchronous or synchronous?

Answer 3

Asynchronous

Question 4

Describe SMTP

Answer 4

Simple Mail Transfer Protocol.
Text Based
Takes message and Header, sends to mail server (POP or IMAP)
Has no authentication- can send emails from any address

Question 5

Describe POP

Answer 5

Post office Protocol
Email is stored on mail server.
Client either downloads and deletes or leaves it there.
Not designed for multiple clients- mail will be deleted from server and cant be seen or you try and delete from one client but it will be on the other

Question 6

Describe IMAP

Answer 6

Internet Message Access Protocol
Has connected and disconnected nodes- cache like
Multiple clients connected to same mailbox.
Email lives on the server and you only have a temporary view. Email client acts like a cache.
Allows you just to view header and decide whether or not to download.

Question 7

How is IMAP different to HTTP?

Answer 7

have to log in and authenticate
change the state of the server i.e. delete
connection remains open until closed

Question 8

Problems with being able to send multiple commands IMAP?

Answer 8

Overload

Should there be a timeout?