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Fundamentals of the Internet and World Wide Web Fundamentals of Electronic Mail © McGraw Hill 2002. All rights reserved.

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Presentation on theme: "Fundamentals of the Internet and World Wide Web Fundamentals of Electronic Mail © McGraw Hill 2002. All rights reserved."— Presentation transcript:


2 Fundamentals of the Internet and World Wide Web Fundamentals of Electronic Mail © McGraw Hill 2002. All rights reserved.

3 Advantages / Disadvantages of Electronic Mail Advantages  convenient  fast  inexpensive  very reliable  becoming universal  can be printed  informal  environment friendly Disadvantages  not everyone is on-line yet  lost mail  might be viewed by others  forgeries  SPAM  no response  too informal

4 Spam Unsolicited, junk email Costs to Internet community:  Kills legitimate messages  Wastes your time reading through it  Compels service providers to buy extra equipment to cope with spam-driven surges Spam attacks are on the rise:  Email marketing is cheap  Spammers have gotten clever about harvesting email addresses and evading filters  Spammers have increased their volume because filters are better at blocking

5 Spam (con’t) – Origin of spam Origin  Laurence Canter – “father of modern spam’  April 12, 1994 - Husband and wife (Martha Siegel) team of immigration lawyers from Arizona sent out mass mailing over the Internet promoting their services  Green card lottery notice reached thousands of people using USENET newsgroups  Made between $100,000 and $200,000 with $0 cost  Drew criticism from Internet purists but commercial opportunities attracted attention and spam takes off

6 Spam (con’t) – Origin of name Origin of name “spam” for junk email:  1937 - Spam (short for “Spiced Ham”) is Hormel Food Corp.’s name for its canned pork product.  1970 – Monty Python performs their comedy skit where a couple goes into a diner and painfully discover that all the items on the menu contain Spam (canned ham) while in the background Vikings are chanting “Spam! Spam! Spam!”  1994+ - The unsolicited, junk email that has become prevalent was dubbed spam by the original Internet techies, apparently some of whom were Monty Python fans.

7 Spam (con’t) – Acquiring addresses How spammers get addresses:  You provide it when you register at various sites  Harvesting Webpages and Newsgroups anything of form mailto urls  Social engineering – e.g., greeting card sites  Guessing

8 SPAM – A Selected Spam Glossary (from Boston Globe Magazine – Neil Swidey, Oct. 5, 2003) SPAM – Unsolicited bulk email, unsolicited commercial email, or both. HAM – “Good” email FALSE POSITIVE – When a filter makes a mistake for spam (thinks it is spam but it is not) BAYESIAN – Type of filter (based on a mathematical theorem called Bayes’s Rule) that determines the likelihood that an email message is spam by combining the spam probabilities of multiple words, or “tokens.” RULES-BASED – Type of filter (generally less effective) in which a computer is fed certain “rules.”

9 SPAM – A Selected Spam Glossary (from Boston Globe Magazine – Neil Swidey, Oct. 5, 2003) – con’t. HONEY POT – An email account that is designed solely to attract spam so that filter writers can figure out how to smoke out spammers. DICTIONARY ATTACK – Method spammers use for collecting email addresses in which a program generates various combinations of letters and numbers in an attempt to find active email addresses. HARVESTING – Another method spammers use to gather email addresses, in which software “scrapes” the Web looking for email addresses posted on Web pages and in Internet chat rooms and newsgroups.

10 SPAM – A Selected Spam Glossary (from Boston Globe Magazine – Neil Swidey, Oct. 5, 2003) – con’t. OPEN OR CLICK-THROUGH RATES – The percentage of recipients who actually open a spam message, click on the link contained in it, or, in some cases, click through a certain number of pages at the destination website. PHISHING – Method that spammers use to collect people’s personal information for identity theft and credit card fraud by setting up Websites designed to look like those run by legitimate companies.

11 Spam – What to do… What to do if you receive spam:  Don’t reply to spam email  Don’t reply to any “opt-out” email address  When registering at a company’s Website, read the privacy policy and look for opt-out check boxes.  To protect against spam, use a disposable email account when registering.  Use spam filtering software; e.g. – SpamAssassin  Report spam to service providers – might be able to prosecute under the “Can Spam Act of 2003” “Controlling the Assault of Non-Solicited Pornography and Marketing”)

12 Userids Also referred to as user name or account name Uses some algorithm to create unique userids Examples: ehepp, lsa

13 Passwords Authenticate you to computer Use upper/lower case, numbers, special characters Make it at least 6 characters long BAD examples for ehepp: 0225, hepp, 32goss, 1623 Requirements when selecting new password often are as follows:  6 – 8 characters long  At least 1 uppercase letter (A – Z)  At least one lowercase letter (a – z)  At least one digit (0 – 9)  At least one non-alpha-numeric (like ! ? “ $ # ( ) etc.)

14 E-Mail Addresses Basic form username@hostname.subdomain.domain Example: Ray Tomlinson at Bolt, Beranek, and Newman chose @ sign Used to locate username’s mailbox (to the left of the @ sign) Address of computer is to the right of the @ sign Address of computer gets more general from left to right

15 Domain Names A way to uniquely identify computers on the Internet Limited number of top-level generic domain names (gTLD) in the United States:  com, edu, gov, int, mil, net, org  aero, biz, coop, info, museum, name, pro *newer* Each country also has its own top-level domain name (ccTLD):  - site with list of country codes  au, ca, jp, fr, de, … Approx. 250 top-level domain names ICANN (Internet Corporation for Assigned Names and Numbers) – private sector, non-profit corporation created in 1998 to assume responsibility for IP address space allocation and gTLD and ccTDL management

16 Domain Name System (DNS) Addressing system developed by Sun Microsystems in the early 80s A small piece of Domain Name Space appears as an inverted tree Uses distributed naming scheme

17 Finding E-mail Addresses Ask person directly Do an on-line search Guess

18 Remembering Addresses - Using Aliases Local aliases  aka private aliases  Created by you using address book feature, nickname feature, or contacts Systemwide aliases  aka public or global aliases  Usually created by the system administrator  Creates a buffer against change  Makes it easy to find someone Conflicts between local and systemwide aliases – local over-rides systemwide

19 Parts of an E-mail Message Header Body  Greeting  Text  Signature Attachments

20 Composing E-Mail Template – fill in To, Subject, Body content, file(s) to attach; your email address and date/time is filled in for you Netiquette  SHOUTING  emoticons :-) :-P :’( :-0  acronyms btw, fyi Composition  style  signatures

21 Composing Email Signatures Email Signatures  Automatically appended to each email you compose  Consists of some combination of: Name Contact information Affiliation Pithy quote ASCII (American Standard Code for Information Interchange) art; see ASCII Generator ( or Joan Stark’s ASCII Art Gallery (

22 Composing Email Signatures – con’t Ellen Hepp Ellen Hepp CS403 Sections 01, 03, 04 Nesmith Hall Rm. 325 University of New Hampshire Ellen Hepp “Be Here Now”

23 Mailer Features Compose  Subject  Bcc, Cc  Attach  Insert Address Book  aka Nicknames, Contacts  Local aliases  Distribution lists Reply  Bracketed text – include original email for context; delete non- essential info  Reply to everyone or reply only to sender Forward File  Delete  Save to folders

24 3 Components Necessary for E-mail Mail program:  examples: Pine, Microsoft Outlook, Eudora, elm  generically referred to as: mail client, mailer, mail application Mail server – 24x7 machine Mailbox:  Identified by your account name  Specially formatted file set up for you to hold your email messages – only you read from it; everyone else sends to it

25 Pine - A Mail Program Developed at U of Washington in 1989 for e-mail Acronym for Program for Internet News and E-mail Keyboard/menu driven (no GUI) Offers extensive on-line help Why Pine?

26 How E-Mail is Sent 3 components work together (mailer, mail server, mailbox) using protocols Protocol - agreed upon set of conventions that define the rules of communication E-mail is routed using SMTP (Simple Mail Transfer Protocol) over the Internet

27 Store and Forward E-mail Retrieval E-mail is routed using SMTP (Simple Mail Transfer Protocol) over the Internet. Message is stored on the mail spool. POP (Post Office Protocol) is used to retrieve the e- mail:  POP client polls POP server for new e-mail  POP server forwards the e-mail to mailbox

28 Central Mail Spool and IMAP Useful when it is necessary to access mail from several computers Leaves e-mail in a central location IMAP (Internet Mail Access Protocol) resolves conflicts when using central mail spool

29 Lost / Bounced E-mail Invalid user account name Invalid domain name Domain name server is down Other malfunctions

30 Managing E-mail “ I believe in opening mail once a month, whether it needs it or not.” - Bob Considine Recommended strategy Vacation programs E-mail and privacy

31 MIME Acronym for Multipurpose Internet Mail Extensions ASCII (American Standard Code for Information Interchange) vs. binary Simple MIME types: .gif .jpg .txt .wav

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