Re: Mail Data termination

Randall Gellens wrote:
> At 8:20 PM -0400 8/16/11, Hector Santos wrote:
>
> >  NO QUIT means a cancellation because otherwise the only other way to 
> > end a SMTP session is for the client to close the socket connection.
> To me, this sounds like a confusion between POP and SMTP.  In POP, not 
> sending a QUIT cancels any pending deletions.  In SMTP, each MAIL 
> transaction stands alone.  Sending a QUIT at the very end is required, 
> but failing to do so has no ill effects (and there are a number of 
> clients who don't bother).
Excellent point Randall, but rest assured it is not issue of 
confusion. In POP3, issuing an QUIT is a requirement in order to move 
the backend into update mode (either to delete or marked mail received 
depending on the backend mail storage policies). There is no question 
about this handshaking requirement.
For SMTP, IMTO, it is an issue of mixed 821 vs 2821 mindsets, old vs 
new era and an old era that worked under a design presumption on no 
errors - mail was RFC822 valid, the state machine as always in sync, 
no reason to presume a redundant sequence of 500 or more command 
unknown responses has a special meaning and could cause a server to 
drop the line versus an era where it all does have a meaning for 
following strong SMTP compliancy.
Just consider if we are saying that a 250 is all a client needs to 
see, the current SMTP MUST for a QUIT is no longer required and all 
clients can just simply drop the line.
I am only seeing this with what appears to be older software. Other 
senders will retry even after a 250 if they can not issue a SMTP 
required QUIT.  If the server dropped the line because of all the 500 
responses, these senders will retry regardless of the 250.
So its not just my interpretation. If a session can not be gracefully 
completely, 5321 senders will retry if they are not mixing it up with 
a SHOULD as stated in 821.

--
Sincerely

Hector Santos
http://www.santronics.com