how email work

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INFORMATION TECHNOLOGY

INFORMATIONTECHNOLOGYHOW EMAIL WORK

9/22/2011

Binary University College

NAME

ID NUM

COURSE

NUM

CHONG ZI FENG

930102- 14- 5421

Diploma Business Administration

013- 2349888




HOW EMAIL WORK

Introduction

In now day the internet is the most active communication system on the world. People

can get all the information from the network. The communication between family or

friends are also will become more close through internet. Some of them usually are

using the mailing system like email.

From the user standpoint email seem easy and simple to work, because that is just the

sender create and send a mail to the recipient by just select the email address and click

„send‟.

But in reality, that is not only those simple work in mail. The email actually shall

through a lot of process and transfer after been sent. The process included many agent

of the network or the network cloud which server are responsible by a network

company.




HOW EMAIL WORK

How Email Really Work?

This is the most simple diagram shown how the human being using their company

account to send an email to other different network company, that shown there are

containing at least 6 steps of process from sender to the recipient.




HOW EMAIL WORK

Step A: Sender Creates and Sends an Email

By following the diagram the step A shown the sender start to send a email to another

email user. The sender will start to create a mail in their MUA(Mail User Agent) and

select the address where they want the email send to and click the word „send‟.

MUA ( Mail User Agent )

MUA refers to a network company which the user is having an account and satisfying

the internet service included the mailing system. They are responsible and application

to help the members send, receive and read the email.

For the example of those company like : Window Live Messenger, Yahoo and so on.




HOW EMAIL WORK

Step B: Sender‟s MDA/MTA Routes the Email

After the sender create and sent the mail through MUA, the MUA will deliver the

mail to the sender‟s MDA(Mail Delivery Agent) or the sender‟s MTA(Mail Transfer

Agent) then to the network cloud.

What is MDA and MTA?

Mail Delivery Agent refers to the agent of received the mail where MUA sent and

makes process and transfers the mail to the MTA or network cloud.

Mail Transfer Agent also responsibilities for what MDA handles. Both of two

servers are almost doing the same work by different name.

Why the MUA need to deliver the mail to the MDA/MTA?

The MUA is just one of the network company on the whole internet, there are

containing so many other network company to provide mailing service. And the

mailing service not only will send or receive the email come from the same network

company, they are also will send and receive the email with other different network

company, so they must through more than one MTA to send or receive both mail to

the other MUA.

Condition same as the Window Live Messenger user sends a email to the Yahoo user.




HOW EMAIL WORK

Step C: Network Cloud

Inside the Network Cloud can be some of the network company or ISP (Internet

Service Provider. It is having a lot of mail server, routers and other devices or

services inside and application to receive the email from the MTA and load the email

as well. The mail server will process the mail by loading with a long time meaning the

size of file is large and it unable to receive an email when taken down for

maintenance, and sometimes may not have identified themselves properly to the

internet through the DNS (Domain Name System) so that other MTAs in the network

cloud are unable to deliver mail as addressed.

Some of the email services provider they have their own Network Cloud when their

companies are process a large volume of email.

DNS (Domain Name System)

A system of application to identify the address of an email which it receive from the

MTA in the Network Cloud. Every mail need to through DNS then just only continue

to the next MTA.

Network Cloud

Routers/Serve

Routers/Serve

Routers/Serve

DNS

Routers/Serve

Routers/Serve

Routers/Serve




HOW EMAIL WORK

Email Queue

When an email that is addressed to another difference email service companies as the

diagram given, it may enter the email queue with other outgoing message.

The email will through the queue what called Central Gateway with other mail when

it is ready to transfer to next MTA or Network Cloud.

If there is a high volume of mail in the queue either because there are many message

ready to send or the mail unusually large to load, both of the email in queue will be

delay in the queue until to the MTA process.

MTA MTA MTA

Network Cloud/

MTA

Central Gateway

MTA MTA MTA

ueue ueue ueue




HOW EMAIL WORK

Step E: MTA to MTA transfer

When an email is transferring the sender‟s MTA will handles all the aspect of mail

delivery until the mail are either accept or reject by the recipient‟s MTA.

After the mail was finished the queue it will enter the second network cloud( Internet

Network Cloud) where it is routed along a host to host chain of servers.

Every MTA who are transferring an email will “stop and ask” again the DNS in the

second network cloud in order to identify the next MTA in delivery chain.

To find out the IP address and mail box of the recipient the MTA must drill down

through the DNS, which consists of a set of servers distributed across the Internet.

Beginning with the root nameservers at the top-level domain (.ltd), then domain

nameservers that handle requests for domain within that .ltd, and eventually to

nameservers that know about the local domain.

There are 13 root servers serving the top-level domains(e.g,.org, .com, .edu, .gov, .net,

etc,). Those root servers refer request for a given domain to the root name servers that

handle request for that tld. In practice, this step is seldom necessary.




HOW EMAIL WORK

Step F: Firewalls, Spam and Virus Filters

An email should through a lot of the MTA or the network cloud by the same time, the

email also through a lot of the firewalls, spam or virus filters which is set by both

email or internet services providers.

Before an email through a firewalls it has to scan by the spam and virus filters. Both

filters responsible to pass the qualifies files and detect the spam or malware files.

When an email is detected because of the malware reason the mail will be quarantined

and the sender will be inform about the mail was blocked. But if the mail is detect as

the spam files and the files will be block without notifying to the sender.

Virus Filter

Spam

Firewalls

ualified Mail




HOW EMAIL WORK

Delivery

After an email passed all the hazards or process, it finally delivered and reached the

recipient‟s MTA. The recipient‟s MTA now will transfer the email to the third

network cloud which cloud that is belong to the recipient‟s email services providers

and run the process same as other network cloud. After the process of network cloud

the recipient‟s MTA will calls the local MDA to deliver the email to the correctly

address or mailbox, where it will sit until it is retrieved by the recipient‟s MUA.




HOW EMAIL WORK

It‟s like Regular Mail

The construction and delivery of email is similar to regular mail but email is more

modern then a regular mail. An email message constructed same as the regular mail

you‟d send through the postal services, a message enclosed in an envelope. The

envelope header of an email is analogous to the hardcopy letter but the information

contained of an email compare with the regular mail is more detail than a regular mail.

Message Header

An email message header you‟ll see there are included the „From‟, „To‟, „Date‟,

and „Subject‟ fields. The information given by an email was more clearly than a

regular mail as it can define the sender and the date received.

The Date

The email‟s header „Date‟ field is following by the originating MUA, so it will

show the date and time when the sender sent an email.

The Subject

The subject is not really used in regular mail except some of the business formal

letters. But on email cases, that necessary for an email because when an email

without a subject you could not send a mail.

The Reply-To

The envelope header of an email also containing with a „Reply-To‟ by given the

sender‟s address for the receiver to reply the sender. So that was more

convenience for the mail user.




HOW EMAIL WORK

Conclusion

Although the mailing system we use in daily look simple, but its containing a lot of

work behind them we are never know. After both of these research and understanding

finally I known how the email work like, that is more difficult than I thought. By after

the reading it is more process to do than a regular mail. I realize we are lucky to

satisfy both technical implement by born in this era and we shall treasure what we are

satisfying.




HOW EMAIL WORK

References

Information

http://www.oasis-open.org/khelp/kmlm/user_help/html/how_email_works.html

Pictures

http://www.google.com.my/imghp?hl=en&tab=ii







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