UUCP and preservingply-to: how?

[rodney at sabletech.com (Rodney Thayer)]

I think the fat Sendmail book from O'Reilly has prose that discusses this.

Unfortunately I also think you need to read the sendmail sources....

At 10:36 AM 4/4/96 EST, you wrote:
>| Dale R. Worley wrote in a message to Mike Bilow:
>| 
>| Note also that is illegal to use both a '!' and a '@' in a mail address, such
>| as aaaa!bbbb at cccc.  The UUCP side will parse this as "send to aaaa, which
will
>| send it to bbbb at cccc."  The SMTP side will parse this as "send to cccc, which
>| will send it to aaaa!bbbb."
>
>Can you quote chapter and verse in some relevant  standard  for  this?
>I've  often  made  similar  suggestions when I've seen email addresses
>with both '!' and '@', and been rebuffed by the claim  that  "everyone
>knows"  that one or the other meanings is the correct one.  Of course,
>different groups of "everyone" seem to know different interpretations,
>and they can't quote any standard, either.  I've looked around for the
>appropriate standards to point people to, to no avail so far.
>
>In my readings, I've gotten the impression  that  standards  documents
>casually  ignore  such  questions.   After all, why should an Internet
>standard say anything at all about the interpretation '!'?   To  them,
>it's  a non-syntax character, and they'll usually respond by making it
>clear what they think of people who use competing packages like  UUCP.
>Similarly,  any  UUCP standard (if such even exists ;-) is unlikely to
>deal explicitly with '@', since it's not a significant character.
>
>You can make a reasonable argument that,  once  you  admit  that  UUCP
>exists,  there  is a semi-definition that says "foo!joe at bar" should be
>parsed as "foo!(joe at bar)".  The argument goes as  follows:   The  UUCP
>definition  is  that  an  email address is of the form node!recipient,
>where node is the name  of  a  machine  reachable  via  any  transport
>mechanism, and recipient is either 1) a user id known on that machine,
>or 2) an email address that makes sense to the mailer on that machine.
>In case 1), the mail is delivered to the user; in case 2), the mail is
>delivered to the /bin/rmail command for forwarding.  Thus, if you  are
>using UUCP, *any* string is valid after the '!', as long as the mailer
>on the node  can  decipher  it.   Thus,  "foo!(joe at bar)"  is  a  legal
>interpretation  of  "foo!joe at bar",  if you have a UUCP-style mailer on
>your own machine.  Whether it will work depends on whether foo has  an
>rmail command that can parse "joe at bar".
>
>How about the "(foo!joe)@bar" interpretation?  Well, RFC821 says  that
>the only thing legal before an '@' is a user's login id, and "foo!joe"
>isn't a valid login id on any known OS.  Later RFCs have extended what
>is allowed after the '@', to include FQDNs, but they haven't added any
>sort of forwarding syntax for the recipient field.  The '%' kludge  is
>just  that.   It isn't supported by any Internet standard; it's just a
>convenience until we reach the ideal state in which any Internet  host
>can  make a TCP connection directly to port 25 on any other host.  The
>dogma on the Internet is that forwarding isn't  necessary,  since  all
>hosts  can  connect directly to all others.  If this doesn't work, you
>shouldn't kludge the email system, you should fix your network.   Thus
>"(foo!joe)@bar"  is  not a valid SMTP address, and there don't seem to
>be any other email standards that use  '@',  so  this  isn't  a  legal
>parsing according to any standard.
>
>In summary, "foo!(joe at bar)" is a legal parsing of "foo!joe at bar"  using
>the  rules of one known email package (UUCP), while "(foo!joe)@bar" is
>not legal using any mailer's rules.  Whether this is relevant  to  you
>depends on which email package you have installed.
>
>We are, of course, getting further away from the  ideal  of  universal
>interconnection. Once the concept of "firewall" appeared, the game was
>pretty much over; we can safely predict that the  SMTP  dogma  tht  no
>forwarding  is  needed  will  never  come  true.   Still,  if you make
>suggestions in  the  appropriate  newsgroups  about  how  to  do  SMTP
>forwarding,  the  inevitable  result  is  that  you get lots of flames
>telling you what an idiot you are for thinking that such  kludgery  is
>necessary.   Just fix your network, turkey, and it'll all work without
>any forwarding.  And anyway, you shouldn't need to use something  like
>"(foo!joe)@bar", because only an idiot would use UUCP, right? (Only an
>idiot that likes reliable,  configurable  email,  right?)  Well,  I've
>gotten lots of such flames over the years. (They somehow never explain
>how I am to get superuser access to all the other machines on the  net
>so as to implement their suggestions.  ;-)
>
>So I'd conclude that "(foo!joe)@bar"  isn't  a  legal  interpretation,
>because  it implies that SMTP mailers can do forwarding.  Granted, all
>competent mailers *can* do forwarding, but that's  just  an  temporary
>and  unnecessary  kludge, according to the established SMTP dogma.  On
>the other hand, "foo!(joe at bar)" is legal if you have  a  UUCP  mailer,
>because it implies that UUCP mailers can forward to SMTP mailers. They
>can, and it's an officially sanctioned operation in the UUCP arena. If
>you  run  smail,  such  inter-mailer  forwarding is clearly and openly
>supported.  If you don't, well, you are at the mercy of whatever  your
>mailer's authors thought about the whole religious issue.
>
>Now if the programmers that develop email software could be taught the
>uses  of  parens,  as I've done above.  I mean, mathematicians figured
>this out several centuries ago, and most people who build  programming
>languages  have  picked up on the idea.  But just try finding an email
>package that allows the use of parens to disambiguate expressions. Oh,
>well;  I  guess  I  shouldn't gripe too much.  After all, we are still
>being saddled with software written by  people  that  haven't  learned
>about the number zero, and haven't heard of null strings.
>
>
>

                  Rodney Thayer           ::         rodney at sabletech.com
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