On Wed, 2 Feb 2005, Richard Dawe wrote:
The RFC on pipelining (RFC2920
<ftp://ftp.rfc-editor.org/in-notes/rfc2920.txt>) doesn't discuss what to
do on a temporary failure on, say, MAIL FROM.
The pipelining spec is hopelessly wooly.
Consider the following sequence:
MAIL FROM
4xx
RCPT TO
5xx (no MAIL FROM => RCPT TO not valid)
DATA
5xx (no recipients)
What should the SMTP client conclude in this case? Should it bounce the
message or try again later?
It should try again later. The client should interpret the responses as if
it hadn't pipelined the commands. The first error is the important one.
(Outlook gets this grievously wrong and will uselessly report to users
"Valid RCPT command must precede DATA". Not advertising PIPELINING doesn't
help because it pipelines anyway.)
Tony.
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