-I CS-3505 Wb_ -I.ppt

4 The most useful feature of the internet 4 Lots of different programs, but most of them can talk to each other.

How works 4 Two types of programs interact: delivery mail agent & user mail agent 4 What you see on your desktop is the mail user agent, eg, Eudora, Outlook, Netscape Message center 4 Your user mail agent sends mail to the delivery mail agent, eg, Microsoft Exchange, sendmail which sees it gets to the destination

Examples of mail agents 4 Eudora--Windows, Mac, very popular, free ( 4 Netscape message center--already present in Netscape download, free (home.netscape.com) 4 Outlook Express--From MS. Free with Internet Explorer Command line stuff on Unix (elm, pine)

Delivery Agents & User Agents Your PC running mail user agent Outlook Express NPS Mail Server running delivery agent Mail server User PC running mail user agent Eudora,Outlook,etc Running Mail Access Server running Mail delivery agent SMTP POP or IMAP mailbox

Delivering Mail 4 You compose a message on your PC, then hit the ‘send’ button 4 The message is sent to the mail delivery agent at NPS. You must have an account that the mail delivery agent recognizes 4 The MDA saves the message and attempts to deliver it to the destination MDA. The destination MDA may be down, so it can’t be delivered immediately 4 Eventually it gets delivered to the destination server MDA, where it is saved 4 When the recipient wants to read his mail, he downloads it from the Mail Sever MDA to his local PC

Addresses 4 4 Example 4 Server name assigned by the internet naming system implemented by DNS. 4 Local Mailbox name Assigned by local mail administrator as an account 4 Aliases “address book” “nikname” local mailer translation from a short name to the full address

MAIL PROTOCOLS 4 SMTP- Simple Mail Transfer Protocol –See: RFC 821 and RFC 822 – p.htm –MIME MultiPurpose Internet Mail Extension 4 POP, POP3 Post Office Protocol 4 IMAP – Internet Mail Access Protocol 4 Outlook express uses POP3 or IMAP

SMTP Example >>> HELO sun.tuc.noao.edu 250 noao.edu Hello sun.tuc.noao.edu., pleased to meet you >>> MAIL Sender ok >>> RCPT Recipient ok >>> DATA354 Enter mail, end with “.” on a line by itself >>>. 250 Mail accepted >>> QUIT221 noao.edu delivering mail SENDING SMTPSENDING SMTP RECEIVINGSMTPRECEIVINGSMTP

Using 4 Send something –Netscape –Eudora –Outlook Express

Netscape Outlook

courtesy 4 Don’t spam the world 4 Use plain ASCII text if possible 4 There aren’t any physical cues with the text, so it’s easy to be misunderstood. is more informal than a memo but more permanent than a conversation. (See Microsoft trial) 4 Be concise, and to the point

Privacy 4 is not very private. –Stays on MDA servers, where it can be compromised –No expectation of privacy if you’re using your employer’s system for . They can, legally, read your –Password vulnerability –Hard disk compromise

Sending Attachments 4 Sending a file can be tricky. –Cut & paste from word processing document loses formatting –Mail client can’t always interpret format 4 MIME format mail lets you send attachments in any format--the files are passed through exactly as is to the other side

Sending Attachments 4 Eudora--click on the paperclip button 4 Outlook Express: New mail->insert->file 4 Netscape: New message->attach 4 On the receiving side the attachment may be saved in a special directory after being received. In Outlook it is stored in the Personal Folder or Mailbox file

Attachments 4 Most modern mailers support MIME these days 4 MIME is a standard--even mail clients from different vendors can understand it 4 Can be dangerous--since anything can be sent, programs can be sent to. Also Word Macro viruses.

MIME 4 MultiPurpose Internat Mail Extensions 4 Purpose – Converts non ASCII to 7 bit ASCII for transmission over SMTP SMTP MIME SMTP sender receiver 7-bit NVT ASCII Non ASCII codes

Web-based 4 What is it? –Web companies providing free service in exchange for eyeballs 4 Why would you use it? –Distinct from your company’s system –Easy to check on the road--mail servers not always visible from outside the system –More reliable than company mail Yahoo is unlikely to go down or lose network access

Who Provides it? 4 Yahoo.com 4 hotmail.com 4 deja.com 4 whowhere.com

Delivery Agents & Web Browser Your PC running mail user agent NPS Mail Server running delivery agent Hotmail.com User PC running HTML Client Running HTML Server running Mail delivery agent SMTP HTTP Mail database

How does it work? 4 Almost the same as the earlier diagram, but the download from the receiving MDA is done via a web browser instead of a dedicated program like Eudora or MS Express.

Highlights 4 User mail agents interact with mail delivery agents to send mail 4 You can use many different programs and still communicate 4 You can use web-based 4 privacy is not a given

Using Hotmail.com 4 Browser go to

Using Hotmail 4 Inbox, Compose, Address book