At 14:29 17-10-2009, David MacQuigg wrote:
Is it permissible to abort data transfer before the end of data, say
after you have received all headers, and you know the DKIM sig is bad?
RFC-5321 section 3.3 says:
If the verb is initially accepted and the 354 reply issued, the DATA
command should fail only if the mail transaction was incomplete (for
example, no recipients), if resources were unavailable (including, of
course, the server unexpectedly becoming unavailable), or if the
server determines that the message should be rejected for policy or
That paragraph is about the DATA command. You haven't received any
headers yet. You don't know whether the DKIM signature is bad. This is
more of a SMTP question though. You can do anything you wish for policy
reasons. As long as you adhere to the RFC 5321, you won't cause
interoperability or hard to debug problems. I suggest not aborting the
data transfer to avoid such problems.
+1. Aborted Data transfers can cause retransmissions. Unfortunately,
it is better to receive the entire payload and then issue a negative
However, as noted here and you offlist, if there is a DKIM policy
rejection consideration (I presume he meant RC 5617), then he should
be aware of the possible consequences of a SMTP level reject and
consider a message acceptance and silent discard as permitted by RFC
5617 and the new semantics in RFC 5321 as a reasonable reason for
discarding SMTP accepted message deemed hostile.