re: EHLO interoperability problem warning

[Mark Crispin <MRC@xxxxxxxxx>]

Hi -

     I haven't been following the EHLO follies closely, but I noticed John
Klensin's comments about RSET.

     For the EHLO'ers information, I've been badly flamed by people who are
furious at me for including a RSET in the sequence of commands sent by my SMTP
client code.  Since the code allows the SMTP stream to be used for more than
one message, it routinely sends a RSET before starting the MAIL transaction.
It does this to make sure things are cleaned up from a possible previous
transaction.

     Yes, it could check if there really was a previous transition, but it
doesn't; and the transaction code is completely separate from the opening
code.  That is, in the simplest case it sends HELO RSET MAIL RCPT DATA QUIT,
but it could send HELO RSET MAIL RCPT DATA RSET MAIL RCPT DATA ... QUIT.

     Certain individuals have the impression that the correct response to a
RSET is ``close the connection'', and insist that RFC-821 backs them up.  That
seems to be an unusually bizarre interpretation, but by golly they insist that
they Following The Standard (TM).

     It quickly became clear that attempting to reason with such individuals
was hopeless.  I suggested to the hapless client program user that he remove
the line that sends the RSET and recompile as a short-term solution, and find
himself a less anti-social SMTP server as a long-term solution.

     You may want to be aware of this problem in your EHLO debugging.

-- Mark --