Unix mail is an example of electronic mail, which is usually referred to as e-mail. E-mail is becoming an increasingly important way to exchange information as computers are accepted and integreted into the workplace

Because computers have not yet achieved the ubiquitous status of telephones and mailbboxes, e-mail is not a universal solution to your commuinications problems, but it can be a real benefit in many office and personal settings

Avoiding ``telephone tag'' is one good use of e-mail. We can view telephone calls as synchronous communicaions-both participants must be abailable and willing to communicate at the same time. In a typical office setting, this requirement is met less than 30 percent of the time. E-mail is a form of asynchronous communication, which permits individuals to communicate when time is available.

Although the elapsed time for a comple e-mail communication may seem long compared to an equivalent telephone call, it really is more efficient. The benefits of e-mail are numerous. Here are a few: *

You don't waste time making repeated attempts to get through on the telephone.

You don't interrupt someone else's meetings or work sessions.

You can send a message at any time of the day and night.

You can call in from anywhere to read your mail or send mail or send mail to other users if your system has remote acess by phone. *

You can call in from anywhere to read your mail or send mail to other users if your system has remote access by phone.

You can communicate with users on other systems if your system is tied in to a network.

The primary disadvantage of e-mail is that all users must make a conscious effort to check for received mail. If they are logged in full time, the UNIX system can alert them of the arrival of new mail. If they are not operating full time, they must log in periodicaally to check for mail.

Sending and Receiving Mail

I'lllustrate the use of e-mail by using several examples derived from my daily work. Listing 1A shows a sample e-mail message sent to me by an associate. The fact tht some mail is waiting for me is announced when I log in. To read the mail. I type the mail command and carry on a mildly interactive session.

After displaying a message on-screen, mail prompts me by showing a questionm mark on-screen and waits for a command. mail recognizes single-character commands. By pressing d, I tell mail to delete the message. Because it was the only message waiting to be read, mail quits and returns control to the shell. Had there been other messages, they would have been displayed one at a time.

If you are using mail and you forget the commands or haven't learned them yet, you can type the ? command to display a summary of the mail commands (see Listing 1B).

You can delete or save mail messages, send mail to other users, and move forward and backward through your received mail by using these commands. For example, to save a mail item, type s followed by by a file name from the file name with a space or tab. This command appends the current message to the named file (or creates the file if it doesn't exist). If you don't provide a file name, mail uses the name mbox in your system by typing the mail command with an argument that is the log-in name of the recipient. Listing 1C shows my reply to the previously received mail item. I used the log-in name dab because that is the name in the ``From...'' line in the message I received. This name is the equivalent of a return address on a mailed envelope.

The commanmd lets yuou prepare mail messages by thaking your input from the keyboard. You nsimmply type the text of your message. If you make a mistake on a line, use a combination of backspaces and retyping to correct the mistake before presing ther Enter orReturn key. You cannot go back once you have moved to new line. End your input by typing a dot(.) on a line by itself followed by Return. (Note: some UNIX mail programs don't recognize the dot to end input. If you press dot and Return and find that mail is waiting for more input, type Control-D to terminate input).

If your mail session is interrupted, or if you attempt to send mail to a non-existent log-in name, the text of your message may be preserved in a file called dead.letter in your home directory. You can edit the file and then send it using the method described next.

You can also prepare mail messages ``off-line'' by using your favorite editor. (If your editor is a word processor, be sure to create a plain ASCII text file.) This method gives you more control over the message appearance because you can go back and edit the message as much as you want before sending it. After preparing the message and saving it in a file, you send it by using themail command with command-line redirection.

E-Mail to Remote Systems

So far we have dealt with sending mail to users on the same system. If your system can communicate with other UNIX systems, you may also be able to exchange mail messages with users at remote locations.

The key to exchanging mail with remote systems is the availability of UNIX-to-UNIX Copy Programs. UUCP is a set of programs that allow UNIX systems to communicate with each other. If your system is able to call other systems or receive calls from them, you can probably exchange e-mail with users outside your system.

To see whether your system is connected via UUCP to other sites, type the . It will print a list of system names, one per line, that your system can caall. If you are lucky, one or more of these systems might be a backbone site in the UNIX network thqat spans much of the world. Or at least you might have access to another system that connects to a backbone site eihter directly or throught a short seriesof intermediate sites. You may need to enlist the aid of a knowledgeable user or system administrator at your site to find out about your system's connections.

If your system is connected to others, it makes calls on your behalf. You don't need to know any telephone numbers, because the sytem has them in a file that is read by UUCP when it is asked to send mail.

Figure 1A depicts a fictional UNIX network with six sites and shows their connections. The backbone sites have connections (not shown) to many other sites in a larger network. Figure 1B shows some sample mail paths that would be used to addes mail to some users in the example.

The exclamation point (usually caled a ``bang'' separates entries in the path specification. The initial series of entries is a sequence of system names of sites that relay the message to the user. The user's log-inname is the last entry in the path and is preceded by the name of the user's system. You may have to do some digging to find the information you need to form correct mail paths. If UNIX users send you mail, the message will contain the path by which it came. You can usually reverse the sequence of names to reply to the sender.

The standard UNIX mail program is functional and reliable, but it lacks many convenience features that users of Berkeley UNIX have come to expect. The Berkeley Mail command has many helpful features to enhance all aspects of receiving, preparing, and sending mail.

A recent AT&T UNIX program called mailx is very similar to Mailand is available on some AT&TUNIX systems. On some UNIX and XENIX systems, the command name mail is a link (another name) to either Mail or mailx. In the folllowing descriptions, I will use the command name mailx, but the material applies to Mail with little or no change.

One of the features of mailx is the use of a file called .mailrc to customize the program to your preferenmces. When you start mailx, it reads commands and other information from the .mailrc file (in your home directory) and configures itself to your specifications.

You have control over various options by using set (and unse) commands. For example, to select the emacs editor for use in creating mail messages, add the command set VISUAL=/usr/lbin/emacs to your vi unless your system administrator overrides this choice in a system-wide configuration file. (Note: use a correct path name for the editor of your choice in the set VISUAL command.)

You can also create aliases, which are alternatte names thjat mailx translates into full mail addresses. Adding the command alias snowman site2!backa!alaska!gus to your file lets you use the name ``snowman'' in place of the full mail path in mailx commands. This saves you some time and reduices the risk of typing errors.

Another nice feature of mailx is the reply function. After you read a message, you may want to send a reply to the sender of the message. Type the R command to reply only to the sender or r to reply to the sender and anyone else (except yourself) who received the message. The mailx command puts you in the input mode and waits for you to type the reply message. If you want to use a visual editor to create your input, type `v and press the Return key. When you have finished creaating your reply, quit the editor and type dot (or Control-D) to send the reply.

The mailx program has far too many commands and options to cover here. When you decide that you need to know more about mailx (and you will), check the documentation provided with you system. You might also want to get the book UNIX Communications, by Bart Anderson et al., publiched by Howard W. Sams, 1987. It offers in-depth coverage of e-mail, UUCP, and other UNIX communications topics.