From: MAILER-DAEMON@berkeley.edu 83 550 zhang@uni-dortmund.de... User unknown: Not a bicycle 553 abingdon I refuse to talk to myself 554 “| /usr/new/lib/mh/slocal -user $USER”... unknown mailer error 1 554 “| filter -v”... unknown mailer error 1 554 Too many recipients for no message body “Not a typewriter” is sendmail’s most legion error message. We figure that the error message “not a bicycle” is probably some system administrator’s attempt at humor. The message “Too many recipients for no message body” is sendmail’s attempt at Big Brotherhood. It thinks it knows better than the proletariat masses, and it won’t send a message with just a subject line. The conclusion is obvious: you are lucky to get mail at all or to have mes- sages you send get delivered. Unix zealots who think that mail systems are complex and hard to get right are mistaken. Mail used to work, and work highly reliably. Nothing was wrong with mail systems until Unix came along and broke things in the name of “progress.” Date: Tue, 9 Apr 91 22:34:19 -0700 From: Alan Borning borning@cs.washington.edu To: UNIX-HATERS Subject: the vacation program So I went to a conference the week before last and decided to try being a Unix weenie, and set up a “vacation” message. I should have known better. The vacation program has a typical Unix interface (involving creat- ing a .forward file with an obscure incantation in it, a .vacation.msg file with a message in it, etc.) There is also some -l initialization option, which I couldn’t get to work, which is supposed to keep the vacation replies down to one per week per sender. I decided to test it by sending myself a message, thinking that surely they would have allowed for this and prevented an infinite sending of vacation mes- sages. A test message, a quick peek at the mail box, bingo, 59 mes- sages already. Well. It must be working.

84 Mail However, the really irksome thing about this program is the standard vacation message format. From the man page: From: eric@ucbmonet.berkeley.edu (Eric Allman) Subject: I am on vacation Delivered-By-The-Graces-Of: the Vacation program … Depending on one’s theology and politics, a message might be deliv- ered by the grace of some god or royal personage—but never by the grace of Unix. The very concept is an oxymoron. Apple Computer’s Mail Disaster of 1991 In his 1985 USENIX paper, Eric Allman writes that sendmail is phenome- nally reliabile because any message that is accepted is eventually delivered to its intended recipient, returned to the original sender, sent to the sys- tem’s postmaster, sent to the root user, or, in absolute worst case, logged to a file. Allman then goes on to note that “A major component of reliability is the concept of responsibility.” He continues: