EMAIL [3.2 Basic Email Client Operations] - Quick email facts - usually fairly short - usually addresses a single topic - plain text only, although this is changing - usually informal style - messages can be replies to previous messages - messages can be sent to more than one recipient - messages can be forwarded to one or more people - often takes very little time to get from sender to recipient - An email consists of two parts - Header (usually you don't see) - Header contains addressing information (who sent, who receives, times, subject, and the path it took through the internet) - Body (main part) - Email addresses - Two parts: - userid or username - host address - email addresses must be typed exactly correctly, or else your message might not go through - online directories to find people's email addresses, since there's no standard format like postal addresses - Fields you fill in: TO, SUBJ, CC, BCC - Programs that you use to read, send, and manage your email are called email clients or mailers ex: Outlook, Outlook Express, various web-mail clients (yahoo, gmail, hotmail) [3.3 Attachments] - email was originally just plain text, and it worked fine - when people wanted to send binary files (e.g. pictures), MIME was developed - MIME = multi-purpose internet mail extension - allows "attachments" - HTML-enabled mail clients then showed up, allowing people to use fonts and graphics in email just like in webpages - since email is just text, this was no problem because HTML is also text - however, HTML email makes messages much larger, especially when they contain graphics - also a great medium for viruses writers, because there can be malicious code embedded in an HTML webpage sent as an email [3.4 Netiquette and netspeak] - needed because in online dialogues, there are no facial expressions or body language or vocal intonations to help convey your message. - in an email: - Watch grammar and spelling - Be careful with humor; avoid sarcasm - avoid uppercase words (SHOUTING) - avoid leaving the subject field blank - emoticons - keyboard characters that represent emotions - also called smileys - flames - do not type an email in a rage - cannot be undone - *very* easy to become upset and send flames, unlike snail-mail BEHIND THE SCENES OF EMAIL [3.5 Mail servers] - client/server model again - program to use to read email is the client, mail servers take care of the actual sending and receiving (might be 2 different servers) - even if they're the same server, they are two very different operations handled by different pieces of software - generally when you sign up for internet service with an ISP, they will tell you the names of the servers for incoming and outgoing mail; you typically type these in into your email client, or sometimes the ISP will provide a setup program to do it for you (with webmail the servers are built in and not needed) - SMTP - simple mail transport protocol -- very old protocol - for outgoing mail - just need an SMTP server, an email address, and a mailer - when you send a message, your mailer contacts the SMTP server, which looks at the email address, takes out the host address and passes it to DNS, which gives back an IP address - then the email goes through the net as usual, possibly through many different servers - [3.6 Receiving email] - while all mailers support SMTP (pretty much the only way to SEND email), not all support all methods of RECEIVING mail - three main protocols -- HTTP, POP, IMAP - HTTP (same protocol used for webpages) is naturally what you use to read web-based email - your web browser serves as your email client, and the web pages are programmed automatically to interact with the mail servers behind the scenes - POP = post office protocol (POP3) - designed for offline email management, when people still paid by the hour to connect to the net - in other words, it let you read email without being online - POP basically is nothing more than a drop-box for messages while you're offline - when you connect to your POP server, the email is downloaded from the POP server to your computer (and then usually deleted from the server) - the mail can then be read offline, since it's stored locally - main drawback -- once email is downloaded to one computer, since it's removed from the server, you can't read it anywhere else (easily) - example of work/home - IMAP - internet message access protocol - online email management, where the email always remains on the server and is only downloaded to your computer when you want to read it - eliminates the main POP drawback - IMAP clients are more flexible than POP clients because they can work in online mode (most common), offline mode (works similarly to POP) - all regular email operations are available, just messages are permanently stored on the remote server - commercial ISPs typically don't give you IMAP access, since the email must remain on the server which takes up a lot of space - they give you POP, where your inbox is emptied every time you check your email, and all messages are stored on your own computer [3.7 Folders and filters] - People like to organize their mail in folders, in a hierarchical structure (draw) - Filters can automatically move email messages into certain folders when they are received (called routing). - Filters work on recognizing keywords in an email address, subject line, or the body of the message - People who get LOTS of email like filters because it automatically sorts their email so they can deal with the exact messages they want first, and leave others to later. - You can of course do this manually with a small volume of email - Email clients have various ways of creating filters - example: filter for discussion group messages for this class - example: spam filter - better to send spam to a special folder rather than delete it [3.8 Web-based email] - every major portal on the internet usually offers web-based email to maximize repeat visits to their site - typically supported by banner ads - nice features - read mail with your browser, supports HTML, similar to IMAP in that email is always stored on the company's servers so you can read it from anywhere - can become bogged down with the number of people using them - can cause email to take a long time to arrive - web-based email accounts work great as a second email address for signing up for things online when you don't want to provide your REAL email address (might get spammed) [Above & Beyond, ch 3] - Spam = unsolicited email sent to a large number of people - just like junk email in snail-mail - except MUCH cheaper - estimates that in 2005, 39% of all email is spam - don't reply to spam, even with 'unsubscribe here' -- typically that just validates your email and gets you more spam - some spammers fake the headers so email looks like its coming from a reliable source (even yourself) - strategies for defending yourself against spam - DELETE button - keep your email address from appearing all over the web - filters - report it to your ISP, boycott companies that send spam or don't respect customers privacy