vacation and SMTP

   Hello,

   On my last mail, how to apply sieve's reject towards a mail  
envelope, containing more than 1 recipients, the very right approach  
is to use PRDR - Per Recipient Delivery Response,  
http://www.ietf.org/internet-drafts/draft-hall-prdr-00.txt . The next  
option is to do what Arnt suggested (first RCPT TO: -> 250 OK,  
consequent RCPT TO: -> 4xx temporary error).
   And now I would like to ask for your opinion about providing a  
standard way to send vacations over smtp and reflecting this standard  
way on the design of sieve-vacation.
   The idea is similar to DNS: when the recipient will not get the  
message (immediately), an error message is sent - first during the  
SMTP dialog, later in form of bounce. The problem with the bounces is  
that they might end in spamtrap, blacklisting the server, which sent  
them. Out office messages are a kind of bounces, and moreover they  
shall not be sent in response to mails coming from , -owner@,  
listserv@, etc, and shall go to the one who actually sent the message,  
not the one that are in the envelope's From: (read faked by spammer).
   In this similar case the reject approach was extended to react  
even during SMTP dialog, thus abolishing the (non-existent, but cool)  
possibility to generate MIME/html messag bounces for rejected mails  
already in sieve.
   What about inventing a new SMTP extension, new response SMTP code  
and giving back as response during the SMTP dialog, that the recipient  
is on holiday? In this way the sender's MUA will have a standard way  
to interpret the message, incl. translation to the local language. My  
suggestion is to include in sieve-vacation a tag for "valid till" and  
"alternative ways" (URLs, like tel:+123, or mailto:my-secretary)to  
contact the sender (and possibly a tag for "valid from"). Then this  
response is interpreted somehow and the original sender sees in her  
language till when the person is not available.
  A side effect there will be no :mime option applicatable, but  
giving a smtp response "550 I don't want this mail" doesn't offer it  
neither.
  Imagine something like this:

  EHLO
  250 OK
  MAIL FROM:<Petra>
  250 OK
  RCPT TO:<Carsten>
  299-unavailable-till"Wed, 18 Jul 2007 19:21:55 -0400"
  299-reachable-at "tel:+123456789"
  299-reachable-at "sms:+987654321"
  299 I am out of office, but will come to your mail once I am back
  DATA
  If you don't react today, we'll miss the contract.
  .
  250 OK

optionally with 299-unavailable-since"Wed, 11 Jul 2007 19:21:55 -0400"  
in between.
  Extending vacation with "valid till" will enable to automatically  
turn off the responses on Friday 17.00, even if one will be  
unavaileble till Sunday. And mailing lists will be able to recognize  
one is unavailable and not-unsubscribe her if the respecive mailbox is  
unfunctional (full) in the meantime.
  Greetings,
    Dilyan