8.1 Electronic Mail
II. The six Internet Services (Revolutions):
Electronic Mail
Mailing Lists
Terminal Emulation
File Transfer (Anonymous FTP)
Usenet (Newsreaders)
World Wide Web (Web Browsers)
III. Electronic Mail
1. The basis for the Internet Mail System is the SMTP Transport Agent [sendmail]
2. Your interface to Unix Mail System is the user agent [mail, mailx, elm, pine, MH, mailtool]
3. Your interface to Single PC (and Macintosh) based Mail (when connected to a
LAN) is the user agent [Pegasus (P-mail) and POP (Post Office Protocol) ]
* Benefits: + mail stored on the PC, not the host
+ agents use DOS function keys or MAC graphical user
interface features
+ easier to learn
* drawbacks: - Lack of Security (No passwords on PC)
- Can't read mail remotely to PC only physically at PC
- Not a universal mail agent (like unix mail is)
4. Mail actions: ¥ Reading ¥ deleting ¥ saving ¥ replying ¥ forwarding
5. Mail Notes:
* Be careful what you say in print to others in your mail. After it leaves
your computer system, you are no longer in control of who reads it, copies it,
forwards it, or takes offense.
* When you receive a message, you don't know who else got a blind copy.
* Once you mail a message, there is no way to get it back, even if it has not
yet been delivered.
* E-mail lives much, much longer than the emotions that motivated it.
Be careful what you write and send! Don't send E-mail you wouldn't want to
see a year from now.
* Don't assume that mail that you send or get is private.
* Some mail are form letters generated for your information and action but
don't require a reply.
* E-mail is analogous to talking on the phone or in person, but with fewer
communicational cues. Thus the need for "Smileys" e.g. :-)
* Make your Subject lines short (40 characters or less) and interesting so
your recipient will want read the message.
Compare:
Subject: "Your office is being demolished tomorrow"
with:
Subject: "Upcoming infrastructural modification"
6. Sending E-mail to someone else:
* Specify one or more userid and domain addresses
* Specify who gets copies of the message
* Specify who gets a blind copy (bcc:) of the message
7. In UNIX, you can specify an alias name to represent a distribution list of
who gets a mail message. (alias is entered into your .mailrc file)
8. In UNIX, you can specify a mailing list of one or more userids who are all
to receive the same mail. An administrator handles the list and handles new,
removed list entries.
9. E-mail consists of a mail header and a mail body.
* Mail Headers contain lines of "envelope" information about the message
* Mail Body contains the ASCII text of the message (Binary data cannot be sent
directly)
10. Typical Mail Header:
**From katz@hcc-cis.ctc.edu Mon May 5 00:00 PDT 1997
Received: by hcc-cis.ctc.edu
(1.38.193.5/16.2) id AA29536; Mon, 5 May 1997 00:00:05
-0700
Return-Path: <katz@hcc-cis.ctc.edu>
Received: by hcc-cis.ctc.edu
(1.38.193.5/16.2) id AA29532; Mon, 5 May 1997 00:00:03
-0700
**Date: Mon, 5 May 1997 00:00:03 -0700
From: Robert Katz <katz@hcc-cis.ctc.edu>
**To: unix215net@hcc-cis.ctc.edu
**Subject: [unix215net] re: upcoming midterm
Sender: katz@hcc-cis.ctc.edu
Precedence: bulk
Status: RO
Mail Body (The message) follows. Double Starred items are required mail
header lines
11. Sending Binary Data through the mail (anyway)
* Binary data may consist of executable programs or program-encoded data or
color pictures or sound recordings.
* Most mail programs (user agents) can't send binary directly.
So, they can be encoded in ASCII format via a UNIX program called uuencode
(uudecode) sent as a regular message, and then decoded at the other end.
* Another protocol called MIME (Multipurpose Internet Mail Extensions) can be
used to send binary data directly.
* Modern versions of newer mail programs support the MIME Protocol. In
these, you attach the binary file (rich text) to your message (and the
recipients mail program separates the binary data attachment into a file.
12. UNIX Mail Hints (Compose Mode):
* To abandon a composed message in the middle, type <CTRL-C> twice.
* If you send mail to an invalid address, the message will be sent back to
you with an explanation. This may take some time to get it back. The
message has bounced back to you.
* How to sometimes tell if a message has been read by the recipient in UNIX.
$ finger jacques@halcyon.com
[halcyon.com]
login name: jaques In real life: John Smith
Phone: 360-484-1313
Directory: /home0/jacques Shell: /bin/ksh
--> Last login Wed Jan 19 21:20 on ttyp4
--> New mail received Thu Jan 20 12:39:22 1995;
--> unread since Wed Jan 19 21:45:11 1995
No Plan
* How to check to see if new mail has arrived in UNIX.
(1) $ from
From addie@nipper.com Wed Jan 21 23:49:50 1995
From joad@fuzzball.edu Thu Jan 22 07:12:06 1995
(2) $ biff [y/n] # use xbiff in X window System
# Is biff keeping track or not use biff
(3) Login to UNIX; the shell gives a: "you have [new] mail" message
when you do
13. UNIX Mail Management hints
* Dispose of messages as soon as you've read them, otherwise they pile up and
get out of hand.
o For each message read, decide if you want to reply and do so right away.
o Before you move on to the next message, either delete or save the one
you just read.
o When in doubt, throw it out [delete the message].
* When your mail program uses a browser (paging) program, get the next screenful
of data [in more, less] by pressing the SPACE BAR; use the RETURN key in pg.
* If you want to save messages from a number of people, use files named after
the people.
s barb when receiving a message from barb to the file named barb
Each time you send a message to barb, send yourself a copy. then save the
copy to the barb file via s barb
In this way all mesages sent or received are in the barb file
* On some commercial internet provider UNIX systems, the storage space used by
unread messages in your mailbox is billed to you. :-(
* To later reread messages that were read, but no disposition made, invoke
the mail program
$ mail -f mbox
Questions? Robert Katz: katz@ned.highline.edu
Last Update December 7, 1999