Subject: Returned Mail: User Unknown 69Date: Thu, 13 Sep 90 08:48:06 -0700
From: [email protected]
Comment: Redistributed from CS.Stanford.EDU
Apparently-To: <Juan ECHAGUE e-mail:[email protected] tel:76 57 46
68 (33)>
Apparently-To: <PS:I’ll summarize if interest,[email protected]
ford.EDU>
Apparently-To: <[email protected]>
Apparently-To: <Thanks in [email protected]>
Apparently-To: <for temporal logics.Comments and references are wel-
[email protected]>
Apparently-To: <I’m interested in gentzen and natural deduction style
[email protected]>STEP 2: Parse the address.
Parsing an electronic mail address is a simple matter of finding the “stan-
dard” character that separates the name from the host. Unfortunately, since
Unix believes so strongly in standards, it has (at least) three separation
characters: “!”, “@”, and “%”. The at-sign (@) is for routing on the Inter-
net, the exclamation point (!) (which for some reason Unix weenies insist
on calling “bang”) is for routing on UUCP, and percent (%) is just for good
measure (for compatibility with early ARPANET mailers). When Joe
Smith on machine A wants to send a message to Sue Whitemore on
machine B, he might generate a header such as
Sue@bar!B%baz!foo.uucp. It’s up to sendmail to parse this nonsense
and try to send the message somewhere logical.
At times, it’s hard not to have pity on sendmail, since sendmail itself is the
victim of multiple Unix “standards.” Of course, sendmail is partially
responsible for promulgating the lossage. If sendmail weren’t so willing to
turn tricks on the sender’s behalf, maybe users wouldn’t have been so fla-
grant in the addresses they compose. Maybe they would demand that their
system administrators configure their mailers properly. Maybe netmail
would work reliably once again, no matter where you were sending the
mail to or receiving it from.
Just the same, sometimes sendmail goes too far:
Date: Wed, 8 Jul 1992 11:01-0400
From: Judy Anderson <[email protected]>
To: UNIX-HATERS
Subject: Mailer error of the day.