E-Mail SMTP (Simple Mail Transfer Protocol)

• standard protocol in TCP/IP suite for transferring mail.

• mail created by user on user agent program

• each message has header that contains recipient’s e-mail address and other information.

• also contains a body that carries the main message message then queued in through SMTP sender program (normally a server program on the host).

E-Mail

E-Mail: How it works• Step A: Sender creates and sends e-mail

through their Mail User Agent (MUA) • Step B: Sender’s MUA transfer the email to

the Mail Delivery Agent (MDA/MTA)• Step C: MDA/MTA accepts the email then

routes it to local mailboxes or forwards it if it isn’t a local address.

• Step D: Network cloud or means it enters ISP or the Internet. The network cloud includes mail servers, DNS servers, routers

• Step E: (Step A,B,C is reversed) upon arrival of e-mail on client side.

E-Mail Types SMTP (Simple Mail Transfer Protocol)

• standard protocol in TCP/IP suite for transferring mail.

• mail created by user on user agent program

• each message has header that contains recipient’s e-mail address and other information.

• also contains a body that carries the main message message then queued in through SMTP sender program (normally a server program on the host).

• each queued message has 2 parts; – RFC 822 header which is a recipients

‘address’. Body of the message.– a list of mail destination.

E-mail : SMTP

MIME (Multipurpose Internet Mail Extension)

• able to transmit binary, text, graphics, audio, video type files.

• solves much of SMTP limitations.

• complies with RFC 822 implementations.

• specification has following elements;

– five header fields defined and provide information about the body of the message.

– Contents format are defined (standardizing representations that support multimedia e-mail)

– Transfer encoding defined.

E-mail : MIME

• The five header fields are;

– Mime-Version : parameter value 1 indicating message conforms to RFCs

– Content-type : describe data contained in body

– Content-transfer encoding : type of transformation that’s used to represent body message so as to be acceptable for mail transport.

– Content-ID : used to uniquely identify MIME entitites in multiple context.

– Content-description : plain text description of object with body.

E-mail : Fraud and types

– Many types of fraud exist, and email is an inexpensive and popular method for distributing fraudulent messages to potential victims.

– According to the US Secret Service, hundreds of millions of dollars are lost annually and the losses continue to escalate.

– Most fraud is carried out by people obtaining access to account numbers and passwords.

– Never respond to any message that asks you to send cash or personal information. You won't receive any riches, and in fact you could get into legal trouble if you become involved with one of these scams.

E-mail : Types of Fraud

• Personal information scams (phishing)

– "Phishing" scams are currently the most popular and thus dangerous form of email fraud.

– They use email messages that appear to come from a legitimate company or institution, such as your bank or university, and ask you to "update" or "verify" your personal information;

– the scammers then use this information to commit identity theft.

E-mail : Bank Scams

• Nigerian bank scams

– A very common type of email fraud is advance fee fraud schemes. The perpetrators of advance fee fraud (sometimes referred to as Nigerian or foreign bank scams) are often very creative and innovative.

– This fraud is also called 4-1-9 fraud after the section of the Nigerian penal code that addresses fraud schemes.

– Nigerian nationals, purporting to be officials of government or banking institutions, will fax or email letters to individuals and businesses in the US and other countries.

– The correspondence states that a reputable foreign company or individual is needed for the deposit of an overpayment on a procurement contract.

E-mail : Bank Scams (2)

• Nigerian bank scams

– Some variations of this scheme have the son or daughter of a murdered official plead for your assistance in depositing an inheritance in a US bank.

– Individuals are asked to provide funds to cover various fees, and also are asked for personal identifiers such as Social Security numbers, bank account numbers, and other similar data.

– Once this information is received, the victims often find that their bank accounts are emptied. It is hard to pinpoint how much has been lost in these scams since many victims do not report their losses to authorities due to fear of embarrassment.

E-mail : Sweepstakes, lottery & Prize scams

• These scams trick you into thinking you've won large amounts of money. You sometimes have to send personal information that is then used to rob you, or you are asked for processing fees for your fictitious winnings. Be suspicious if:

– You know you didn't enter the competition or promotion that you've won.

– You're asked for any sort of processing fee.

– You're asked to buy "low-risk" sharLecture 5es in a fund for purchasing "high-stakes" tickets.

– You are offered bait prizes that are substandard or you're asked to purchase "exclusive items".

– Receipt of your prize requires travel or other arrangements at your own expense.

E-mail : Chain Mail

• Chain Mail is a form of junk mail.

• A chain mail message is generally sent to several people and includes instructions that each person should forward the letter to several others.

• These messages waste system resources and often grow quite large as senders append their own additions.

• Do not forward such messages.

• Email fraud and hoaxes often occur in chain mail.

• Never send money or personal information to people on lists via chain mail, or from whom you've received chain mail.

USENET

• Usenet is a distributed Internet discussion system that evolved from a general purpose UUCP network of the same name.

• Users read and post email-like messages (called "articles") to a number of distributed newsgroups, categories that resemble bulletin board systems in most respects.

• The medium is sustained among a large number of servers, which store and forward messages with one another.

• USENET has given rise to and popularised terms and concepts such as "FAQ" and "spam".

» Source : Wikipedia

UUCP

• UUCP stands for Unix to Unix Copy Protocol, and is a computer program and protocol allowing remote execution of commands and transfer of files, email and netnews between Unix computers not connected to the Internet proper. The UUCP package consists of several programs including uucp, uuxqt (front ends for remote copy and execution), uucico (communication program), uustat, and uuname. Nowadays it is rarely used for Modem communications, but is still used sometimes over TCP/IP.

Mailing Lists• collection of names and addresses used by

an individual or an organization to send material to multiple recipients.

• The term is often extended to include the people subscribed to such a list, so the group of subscribers are referred to as "the mailing list", or simply "the list".

• At least two quite different types of mailing lists can be defined: – the first one is closer to the literal sense, where a

"mailing list" of people is used as a recipient for newsletters, periodicals or advertising.

Mailing list…– Traditionally this was done through the postal system, but

with the rise of e-mail, the electronic mailing list became popular.

– When similar or identical material is sent out to all subscribers on a mailing-list, it is often referred to as a mailshot.

– Mailing lists are often rented or sold. – If rented the renter agrees to use the mailing list for only

the agreed upon times. – The mailing list owner typically enforces this by "salting"

the mailing list with fake addresses and creates new salts for each time the list is rented.

– Unscrupulous renters may attempt to bypass salts by renting several lists and merging the lists to find the common, valid addresses.

Mailing list…– Mailing list brokers exist to help organizations rent their lists.

For some organizations such as specialized niche publications or charitable groups, their client list may be one of their most valuable assets and mailing list brokers help them maximize the value of their lists.

Newsgroup– A repository within USENET where messages are posted by different

users in many locations.– Work : Visit http://en.wikipedia.org/wiki/Newsgroup and read on types of

newsgroup available.

» Source : wikipedia