İng 4 UNIT 13 THE WORK WİDE WEP 3. KISIM

UNIT 13 THE WORK WİDE WEP 3. KISIM

Email Protocols

Although the format of a mail message,

as transmitted (gönderi)  from one machine to another (diğer başka),

is rigidly (direk) defined (tanımlar),

different mail protocols  transfer

and store messages in slightly (biraz )different (farklı )ways.

The mail system you're probably (muhtemelen )used to employs (iş vermeleri) a

combination (birleşimleri ) of SMTP and P0P3 to send and

receive ( almak) mail respectively (belirlenen sıra ile ).

Others may use IMAP4 to retrieve (almak) mail,

Especially (özellik) where bandwidth is limited or expensive.

Simple Mail Transfer Protocol

SMTP is used to transfer messages between one

mail server and another.

It's also used by  email programs on PCs to send mail to the server.

SMTP is very straightforward,

providing only facilities to deliver messages to one or more recipients in

batch mode.

Once a message has been delivered,

it can't be recalled or cancelled.

It's also deleted from the sending server once it's been delivered.

SMTP uses 'push' operation,

meaning that the connection is initiated by the sending server

rather than the receiver.

This makes it unsuitable for delivering messages to desktop PCs,

which aren't guaranteed to be switched on at all times.

In host-based mail systems,

such as Unix and Web mail,

SMTP is the only protocol the server uses.

Received messages are stored locally and retrieved

from the local file system by the mail program.

İn the case of Web mail,

the message is then translated into HTML and transmitted to your

browser.

SMTP is the only protocol for transferring messages between servers.

How they're then stored varies from system to system.

Post Office Protocol

POP is a message-retrieval protocol used by many

PC mail clients to get messages from a server,

typically your ISP's mail server.

It only allows you to download all messages in your mailbox at once.

It works in 'pull' mode, the receiving PC initiating the connection.

PC-based P0P3 email clients can

do this automatically at a preset interval. When

you use your Web mail account to access a P0P3

mailbox, the mail server opens a connection to

the POP3 server just as a PC-based application

would. The messages are then copied into your

Web mailbox and read via a browser.

Since P0P3 downloads all the messages in your

mailbox, there's an option to leave messages on

the server, so that they can be picked up from

different machines without losing any. This does

mean that you'll get every message downloaded

every time you connect to the server. If you don't

clean out your mailbox regularly, this could mean

long downloads. when using a Web mail account

to retrieve P0P3 mail. be careful about leaving

messages on the server - if too many build up,

each download will take a long time and fill up

your inbox. Many Web mail systems won't

recognise messages you've already downloaded. so

you'll get duplicates of ones you haven't deleted.

Internet Mail Access Protocol

IMAP is similar in operation to POP, but allows

you more choice over what messages you

download. Initially, only message headers are

retrieved, giving Information about the sender and

subject. You can then download just those

messages you want to read. You can also delete

individual messages from the server, and some

IMAP4 servers let you organise your mail into

folders. This makes download times shorter and

there's no danger ol losing messages.

SPECIALIST READING

A Find (bulun)the answers to these questions in the Following (aşağıdaki)text.

1 Name three different (farklı) email protocols mentioned (bahsedilen)in the text.

Metinde bahsedilen üç farklı e-posta protokollerini adlandırın.

Ens ; SMTP ,POP3 AND IMAP4

2 Which (hangi )email protocol is used to (eskiden) transfer messases between(tarih) server computers?

Hangi e-posta protokolü sunucu bilgisayarlar arasında iletileri aktarmak için kullanılır?

Ens: SMTP

3. Why İs SMTP unsuitable for delivering messages to desktop PCs?

Neden İs SMTP'I masaüstü PC'lerine iletileri teslim etmek için uygunsuz?

Ans : PCs are not guaranteed(garanti edilmediği) to be switched on (açık kalması)at all times.

PC'ler her zaman açık olması garanti edilmez.

4. Name two host-based mail systems mentioned(bahsettiler) in the text.

Metinde bahsedilen iki ana bilgisayar tabanlı posta sistemlerini adlandırın.

Ens: unix and web mail.

5. Where are email messages stored (depolamak) in an SMTP system?

E-posta iletileri nerede, bir SMTP sisteminde depolanır?

Ans : on the receiving (alan) (local) server

alan (yerel) sunucuda.

6. The mail server opens a connectjon to the
POP3 server. The messages are then copied into
your Web mailbox and read via a brovvser.

7. Advantage: İt allovvs emails to be picked up
from different machines without losing any.
Disadvantage: If too many messages build up,
each dovvnload will take a long time and fiil up
your inbox.

8. i İt allovvs you more choice över what
messages you dovvnload.You can dovvnload
just those messages you vvant to read.

ii You can delete individual messages from the
server.

iii Some IMAP4 servers let you organise your
mail into folders.

iv Dovvnload times are shorter.

v  There is no danger of losing messages.

B-

B Re-read the text to find the ansvvers to
these questions.

1  Mark the follovving statements as True or
False:

a   Different mail systems transfer emails in

different ways. true
b   IMAP4 requires more bandwidth than the

other email protocols. false
c   SMTP is used for sending emails from a PC

to a server.true
d   SMTP delivers messages one at a time. false
e   SMTP does not allow a delivered message to

be cancelled.true
f   SMTP is only one of many protocols used to

send mail betvveen servers.false
g   POP protocol allovvs the user to dovvnload

one message at a time. False

2

A SMTP

B 'Push' operation

C POP

D 'PulT operation

E IMAP

B  1 An email transfer process in vvhich the connection is initiated by the sending

computer rather than the receiving computer.

E 2 A mail transfer protocol that initially only retrieves the message headers.

D 3 An email transfer process in which the receiving computer initiates the connection.

C 4 A simple mail transfer protocol that is used to send messages between servers.

A 5 A message-retrieval protocol that downloads ali email messages at the same time.