The electronic mail system

 

How they work

The electronic mail system can be split into 3 main parts namely:

• mail service
• user agents
• user

Figure 2

A more realistic network representation will look like this;

Figure 3

The transmission of e-mails are governed by protocols.

Protocols involved in an e-mail transmission (via the Internet) undergo an interconnection process OSI. Protocols such as the TCP/IP control the following protocols mentioned in the diagram.

• FTP
• TCP
• IP
• POP
• SMTP
• DNS
• TELNET

 

User Agents

User agents are software for electronic mail, which have the prime function of sending and recieving mail. Most user agents also have:

• Simple word-processing applications; for typing, editing and attaching files from other various program applications.
• Filing systems; for read, unread and archived messages.

User agents can also be incorporated on Internet Service Providers (as most of them do have today) such as Netscape, AOL, Internet Explorer, Lynx, Hotmail, CompuServe and many others.

Domain Names

These are used to represent organisational, geographical or political identities. Examples of domain names are in bold as shown below:

(a.) http://www.open.ac.uk/Students/

(b.) http://www.aol.com/

(c.) http://www.firstclass.open.ac.uk/

Mailbox Name

A mailbox name is a name allocated to a person, a number of people or organisation which fall under a specific organisational, geographical, or political identity.

A mailbox name consists of two parts namely the name of the identifier and the domain name separated by the @ symbol. Examples of mailbox names are shown below and can be seen to be a collection of the identifier name as well as the domain name.

(a.) graphillusions@aol.com

(b.) chi.ajoku@ubsw.com

(c.) chi.ajoku@rodaprint.co.uk

Compatibility

All user agents such as; Outlook Express, Microsoft Outlook, Lynx, or Lotus although display messages in different ways are all compatible with each other. All displays have a common standard as displayed in Fig. 4

A typical Email message

To: T293 KHT Group 1 From: Dipak Subject: Re TMA04 & TMA05 Cc: Chi Ajoku, Andy White

Good evening all, I am not sure where you are with the study but we need to start communicating with each other..... Dipak

 

Figure 4

A summarised relationship between TCP, IP, MTA, SMTP and POP

• The mail service (Email post office) is provided with a server host that works with the help of TCP connections.
• This server host operates on a set of commands or otherwise known as the POP protocol.
  
  

References

Parsons & Oja (2000) 'Computer Concepts' fourth edition, Thompson Learning, printed in USA.

John Monk - extract (2000) 'Communicating Technology - Electronic Effect, The Open University, Walton Hall press.

http://www.protocols.com/pbook/tcpip.htm

http://www.techweb.com/encyclopedia/defineterm

 

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