Electronic Mail Overview

Electronic mail, or email, provides a means for individuals and groups to electronically correspond with each other across the global networks.
Email can be used for more than sending correspondence. Data, images and even computer programs can be sent within mail messages (file transfer). Email is also used as the basis for other Internet services such as mailing lists and newsgroups.
Every UNIX system allows you to exchange electronic mail with other users on your local system. Most systems also allow you to exchange mail with users on remote systems.
Electronic mail is very quick. Messages will reach users on the same system almost immediately; users on systems elsewhere in this country, or other countries, in a few minutes, or hours at most.
The standard UNIX mail utility which comes with most UNIX systems is called, simply "mail". Another improved version, called "mailx" may also be available.
There are a number of other, easier to use and more full featured electronic mail utilities available for UNIX systems. In most cases, these do not come with the standard UNIX operating system, but must be acquired and installed separately.
Using email requires that you understand electronic mail addresses. In most cases, an email address looks something like:
```
     username@somemachine.domain
     
```
How do you find a person's email address?
- Ask them
- Check the "from" field on email which you have received. The from field usually appears in the "header" portion of a mail message. For example:
```
 
From: mbida@mail.mhpcc.edu
Message-Id: <9502232348.AA127930@kanaha.mhpcc.edu>
Subject: 400-way upgrade plan
To: systems@mail.mhpcc.edu, services@mail.mhpcc.edu
Date: Thu, 23 Feb 1995 13:48:50 -1000 (HST)
          
```
- May be able to use an Internet search tool such as "netfind" or "whois"
- UNIX "finger" utility
- Business cards, stationary

Standard UNIX Mail

Mail allows you to
- compose a message and send it
- receive a message and display it
- save messages
- customize certain features
When you are using the mail program you are in one of two "modes". Each mode has its own set of commands.
- send mode - for creating and sending a mail message. Two character commands which begin with a tilde (~) character.
- command mode - for reading and managing mail. Single character commands.

Sending Mail

Sending Mail - basic example
1. Enter the command:
```
     mail username@address 
```
2. You will then be prompted to enter the subject of your mail message. Enter the subject title and press the Return key. If you make a mistake use the Backspace or Delete key for corrections. For example:
```
      Subject: Meeting tomorrow at 1:00 
```
3. Enter the text of your message. Use the Backspace or Delete key for corrections. Press the Return key whenever you want to start a new line. Note: you can not back up to previous lines to make corrections. You will need to invoke an editor, such as vi to accomplish this (covered later).
4. When you are finished typing the message, press the Return key to start a new line and type CTRL-d. You will then be prompted for any addressees to Cc. You may either enter additional email addresses or press the Return key if there is nobody to copy. Your message will be sent and the shell prompt will be displayed.
Begin the Electronic Mail exercises.

Send Mode Commands

Send mode commands: allow you to perform various functions while you are in the middle of composing your mail message.
These commands are two characters, the first of which is the tilde (~) character.
Must be issued as the first characters on a line in order to be interpreted as commands and not message text.
A list of the send mode commands appears below. Note that this set is not universal. Different UNIX operating systems may have a different sets. The set below is for mail running under IBM's AIX operating system.


     Control Commands:
     CTRL-D          - Send message 
     ~q              - Quit editor without saving or sending 
                       message
     ~p              - Display the contents of the message buffer
     ~?              - Display help 
     ~:set           - Show which mail options are in effect 
     
     Add to Heading:
     ~h              - Add to lists for To: Subject: Cc: and Bcc:
     ~t addrlist     - Add user addresses in addrlist to the 
                       To: list
     ~s subject      - Set the Subject: line to the string 
                       specified by Subject
     ~c addrlist     - Add user addresses in addrlist to Cc: list
     ~b addrlist     - Add user addresses in addrlist to Bcc: list 

     Add to Message:
     ~d              - Append contents of dead.letter to message
     ~r filename     - Append contents of filename to the message
     ~f numlist      - Append contents of message numbers in 
                       numlist
     ~m numlist      - Append/indent contents of message numbers 
                       in numlist

     Change Message:
     ~e              - Edit the message using an external 
                       editor (default is e)
     ~v              - Edit the message using an external 
                       editor (default is vi)
     ~w filename     - Write the message to filename
     ~! command      - Start a shell, run command, and return 
                       to the editor.
     ~| command      - Pipe the message to standard input of 
                       command; REPLACE the message with the 
                       standard output from that command.

Invoking an editor, with either the ~e or ~v command makes creating your message much easier. If you use ~v, then the vi editor will be used. If you use ~e, you can use a different editor, such as pico:

     
     ~:set EDITOR=/local/bin/pico  - first specify the editor 
                                     of choice 
     ~e                            - then invoke it

In addition to the ~r command, you can send a file in a mail message as shown below. In this example, the file "asia.report" will be sent to the address jwwilliams@ibm.vnet.com. No editing of the mail message is possible - it will be sent directly.
```
     mail jwwilliams@ibm.vnet.com  <  asia.report 
```
Continue the Electronic Mail exercises.

Reading Mail

To read your mail, simply enter the command:

     mail

If you have any mail in your system mail box, an indexed list of the messages will be displayed on your screen. For example:

     
> 1 pegwms@mhpcc.edu Wed Oct 26 14:49  94/3378 "Suggestions"
  2 tfahey@mhpcc.edu Wed Feb 15 12:17  94/3308 "netfind"
  3 lwaters@mhpcc.edu Wed Feb 15 16:27  29/916 "URL"
  4 colek@mhpcc.edu Wed Feb 15 10:08  46/1784 "New Employees"
  5 bob@soest.hawaii.edu Thu Feb 16 09:11  83/2868 "Images"
N 6 colek@mhpcc.edu Fri Feb 17 08:33  30/1166 "Fill Out Form"
N 7 tfahey@mhpcc.edu Fri Feb 17 09:01  48/1584 "Getting Started"
N 8 pegwms@mhpcc.edu Fri Feb 17 17:34  121/5011 "HPC Asia '95"
N 9 lijewski@HK.Super.NET Fri Feb 17 23:52  30/1229 "hi from HK"
&

In the above example, note that:

> indicates the current message
N indicates a new message
Messages are numbered and sorted by date/time
Message sender is displayed
Message size in lines/characters appears
Subject is displayed
& is the mail prompt, telling you that you are in command mode and that mail is ready to receive a command.

To read the current message, just press the Return key
To read a specific message other than the current message, type the message number. This message will display and become the current message.
To redisplay the message list, use the "h" command
To display the next message, use the "n" command
Continue the Electronic Mail exercises.

Command Mode Commands

Command mode commands: enable you to perform tasks related to reading and managing your mail. These commands will always be entered at the "&" mail prompt. A summary of the command mode commands for IBM AIX mail appears below:

     
     Control Commands:
     q               - Quit - apply mailbox commands entered this
                       session
     x               - Quit - restore mailbox to original state
     ! cmd           - Start a shell, run cmd, return to mailbox
     cd dir          - Change directory to dir or $HOME
     a               - Display list of aliases with addresses
     ?               - Display help
     set             - Show which mail options are in effect
     folder filename - Make filename the current mail folder

     - Display Commands:
     Return key      - Display current message
     t               - Display current message
     t msg_list      - Display messages in msg_list
     n               - Display next message
     f msg_list      - Display headings of messages in msg_list
     h               - Display headings or all messages

     - Message Handling:
     e num           - Edit message num (default editor is e)
     v num           - Edit message num using vi editor
     d msg_list      - Delete messages in msg_list or current 
                       message
     u msg_list      - Recall deleted messages
     s msg_list file - Append messages (with headings) to file
     w msg_list file - Append messages (text only) to file
     pre msg_list    - Keep messages in system mailbox

     - Creating New Mail:
     m addrlist      - Create/send new message to addresses
                       in addrlist
     r msg_list      - Send reply to senders and recipients 
                       of messages
     R msg_list      - Send reply only to senders of messages

Continue the Electronic Mail exercises.

Saving Mail and Using Folders

One of the most useful features of mail is the ability to save mail messages and to organize your mail the way you prefer.
By default, mail will save all messages which you have read to a file in your home directory called "mbox". You can choose to save messages to other files by using the "s" command.
Whenever you save a mail message, it is appended to the file you specify. Files can also be called "folders", since they let you organize multiple mail messages into a common location. Some examples of saving mail into folders appear below:


     s jsmith                - Save current message to file jsmith 
                               in current directory
     s 1-4 projects          - Save messages 1 thru 4 to file 
                               projects in current directory
     s 2 4 5  Mail/old/paul  - Save messages 2,4,5 to file
                               Mail/old/paul

By default, when you start mail, it uses your "system mailbox" as its folder. Your system mailbox is usually located someplace like /usr/spool/mail or /var/spool/mail. It contains new mail and previously unread mail.
You can view other folders by starting mail with the -f option. For example, this command will start mail with the folder "projects":
```
     mail -f projects 
```
While you are in the mail program, you can switch between different folders by using the "folder" command at the "&" prompt. For example, this command switchs the current folder to "Mail/jsmith":
```
     folder  jsmith
```
If you prefer to save all of your folders to a certain subdirectory, and don't wish to type the full name of that directory everytime you save a message or switch folders, mail provides a feature to make this more convenient.
- Set an environment variable called "folder" to point to the directory where all of your mail folders should be kept. For example, the following line could be added to your .cshrc file:
```
     setenv folder Mail/folders
```
- When saving or accessing a folder, precede the folder name with a "plus sign" (+). This will tell mail to use the location specified by your "folder" environment variable. For example:
```
     s +projects

     mail -f +projects

     folder +projects
          
```
Continue the Electronic Mail exercises.

Customizing Your Mail Environment

Mail has many options. The default option settings for your system are specified in a file called:
```
     /usr/lib/Mail.rc
```
Mail allows you to customize your mail environment and preferences. Your customizations are specified in a file you create in your home directory, called ".mailrc". These specifications will override or augment the system defaults.
Some useful mail options are listed below.


     Variable             Action
     --------             -----------------------------
     alias name address   - Creates an alias for a mail address 
     ask                  - Prompts for the subject of each message 
                            sent
     askcc                - Prompts for carbon copy mail addresses
     crt=lines            - Defines the number of lines of a mail 
                            message the Mail program displays before 
                            pausing for input. Works with PAGER.
     EDITOR=editor        - Gives the full path name of the 
                            editor to be started with the e mailbox 
                            subcommand or the ~e mail editor 
                            subcommand. 
     folder=directory     - Directory to save mail files in.
     hold                 - Keep messages that have been read in 
                            the system mailbox, not the mbox file.
     ignore fieldlist     - Specifies which header fields to 
                            not display(ignore) 
     keepsave             - do not delete messages that have been 
                            saved.  Keep them in the system mailbox.
                            Use with the hold option.
     nosave               - Prevents retention of interrupted 
                            letters in the $HOME/dead.letter file. 
     PAGER                - the pager used to paginate output 
                            when a message is longer than the 
                            screen.  Works with "crt" setting.
     record=fileName      - Defines a file in which to record 
                            outgoing mail.
     screen=lines         - Defines the number of lines of 
                            message headers displayed before pausing 
                            for input. 
     topline=number       - the number of lines of the top of each 
                            message to print with the ~t command.
     VISUAL=editor        - the name of the editor called by 
                            the ~v command. Editor is given as a 
                            full pathname.

A simple .mailrc file appears below. Note that more than one option can be placed on a line.


# Simple .mailrc file
#
set ask askcc EDITOR=/source/local/bin/pico folder=Mail 
set PAGER=more crt=20

Continue the Electronic Mail exercises.

Pine: One Alternative to UNIX Mail

Pine is a screen oriented, message handling (mail) tool.
Pine is easy to use - your available commands are clearly visible at the bottom of each screen.
Pine's basic feature set includes:
- View, Save, Export, Delete, Print, Reply and Forward messages.
- Compose messages in a simple editor (pico) with word-wrap and a spelling checker. Messages may be postponed for later completion.
- Full-screen selection and management of message folders.
- Address book to keep a list of long or frequently-used addresses. Personal distribution lists may be defined. Addresses may be taken into the address book from incoming mail without retyping them.
- New mail checking and notification occurs automatically every 2.5 minutes and after certain commands, e.g. refresh-screen (Ctrl-L).
- On-line, context-sensitive help screens.
To start pine at it's main menu, simply issue the command "pine". An example of pine's main menu screen appears here.
Alternately, you can open pine directly into the email composer by using the command "pine user@address". An example of pine's email composer screen appears here.
System wide and personal configuration options can be used to tailor pine's behavior. Your personal configuration options are specified in a file called ".pinerc" located in your home directory.
See the pine man page for additional details.
Continue the Electronic Mail exercises.

This concludes the tutorial. Return to the Table of Contents