Subject: Small wording clarification

From: Philip Hazel <[email-masked]>
Date: Mon, 1 Mar 1999 15:26:35 +0000 (BST)

Today I had occasion to point out this paragraph from 
draft-ietf-drums-smtpupd-09.txt to somebody, who managed to read
ambiguities into the last sentence.

  The MAIL command (or the obsolete SEND, SOML, or SAML commands) begins a
  mail transaction.  Once started, a mail transaction consists of a
  transaction beginning command, one or more RCPT commands, and a DATA
  command, in that order.  A mail transaction may be aborted by the RSET (or
  a new EHLO) command.  There may be zero or more transactions in a session.
  MAIL (or SEND, SOML, or SAML) MUST NOT be sent if a mail transaction is
  already open, i.e., it should be sent only if no mail transaction had been
  started in the session, or it the previous one successfully concluded with
  a successful DATA command, or if the previous one was aborted with a RSET.

Specifically, he queried whether "previous one" means "previous 
transaction" or "previous session". *I* think it is perfectly clear, but 
if people are going to get confused, perhaps it should be recast as

  MAIL (or SEND, SOML, or SAML) MUST NOT be sent if a mail transaction 
  is already open, i.e. it should be sent only in one of the following 
  situations:
    
   (i) No mail transaction has been previously started in the session.
   
   (ii) The previous mail transaction successfully concluded with a 
   successful DATA command.
   
   (iii) The previous mail transaction was aborted by a successful RSET 
   command.  

and perhaps we could change that "should" to "MUST".

The particular cause of this being looked at was an MTA which required 
RSET between successful transactions, which is of course contrary to RFC 
821 and 821bis. Perhaps we could add an explicit statement:

   There is no requirement for a RSET command before starting a new mail 
   transaction if the previous transaction was successful. Software that 
   insists on RSET in this circumstance does not comply with this 
   standard. 

-- 
Philip Hazel            University of Cambridge Computing Service,
[email-masked]      Cambridge, England. Phone: +44 1223 334714.