From: MAILER-DAEMON@berkeley.edu 75 Date: Thu, 6 Oct 88 22:50:53 EDT From: Alan Bawden alan@ai.mit.edu To: SUN-BUGS Cc: UNIX-HATERS Subject: I have mail? Whenever log into a Sun, I am told that I have mail. I don’t want to receive mail on a Unix, I want my mail to be forwarded to “Alan@AI.” Now as near as I can tell, I don’t have a mailbox in my home directory on the Suns, but perhaps Unix keeps mailboxes else- where? If I send a test message to “alan@wheaties” it correctly finds its way to AI, just as the .forward file in my home directory says to do. I also have the mail-address field in my inquir entry set to “Alan@AI.” Nevertheless, whenever I log into a Sun, it tells me that I have mail. (I don’t have a personal entry in the aliases file, do I need one of those in addition to the .forward file and the inquir entry?) So could someone either: A. Tell me that I should just ignore the “You have mail” message, because in fact I don't have any mail accumulating in some dark corner of the file system, or B. Find that mail and forward it to me, and fix it so that this never happens again. Thanks. The next day, Alan answered his own query: Date: Fri, 7 Oct 88 14:44 EDT From: Alan Bawden alan@ai.ai.mit.edu To: UNIX-HATERS Subject: I have mail? Date: Thu, 6 Oct 88 22:50:53 EDT From: Alan Bawden alan@ai.mit.edu … (I don’t have a personal entry in the aliases file, do I need one of those in addition to the .forward file and the inquir entry?) … Apparently the answer to this is “yes.” If the file server that contains your home directory is down, the mailer can’t find your .forward file,

76 Mail so mail is delivered into /usr/spool/mail/alan (or whatever). So if you really don’t want to learn how to read mail on a Unix, you have to put a personal entry in the aliases file. I guess the .forward file in your home directory is just a mechanism to make the behavior of the Unix mailer more unpredictable. I wonder what it does if the file server that contains the aliases file is down? Not Following Protocol Every society has rules to prevent chaos and to promote the general wel- fare. Just as a neighborhood of people sharing a street might be composed of people who came from Europe, Africa, Asia, and South America, a neighborhood of computers sharing a network cable often come from dis- parate places and speak disparate languages. Just as those people who share the street make up a common language for communication, the computers are supposed to follow a common language, called a protocol, for commu- nication. This strategy generally works until either a jerk moves onto the block or a Unix machine is let onto the network. Neither the jerk nor Unix follows the rules. Both turn over trash cans, play the stereo too loudly, make life miser- able for everyone else, and attract wimpy sycophants who bolster their lack of power by associating with the bully. We wish that we were exaggerating, but we’re not. There are published protocols. You can look them up in the computer equivalent of city hall— the RFCs. Then you can use Unix and verify lossage caused by Unix’s unwillingness to follow protocol. For example, an antisocial and illegal behavior of sendmail is to send mail to the wrong return address. Let’s say that you send a real letter via the U.S. Postal Service that has your return address on it, but that you mailed it from the mailbox down the street, or you gave it to a friend to mail for you. Let’s suppose further that the recipient marks “Return to sender” on the letter. An intelligent system would return the letter to the return address an unin- telligent system would return the letter to where it was mailed from, such as to the mailbox down the street or to your friend. That system mimicking a moldy avocado is, of course, Unix, but the real story is a little more complicated because you can ask your mail program to do tasks you could never ask of your mailman. For example, when responding to an electronic letter, you don’t have to mail the return enve-