On Oct 17, 2009, at 2:29 PM, 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's talking about returning a failure response after you've received
the entire body, I believe. You can't do that before the end of data.
I think you're talking about simply dropping the connection. If you did
that most MTAs would retry the delivery.
Failed DKIM would be a policy reason.
(As an aside, you're not likely to want to discard or reject mail due to
a failed DKIM signature, for a bunch of reasons that are more on topic
for the dkim list. Some specific types of failure might be cause for
maybe, but not ones I'd expect you to see much.)