At 08:03 19-10-2009, David MacQuigg wrote:
Forget about DKIM. What if there is some other reason to abort,
like the payload is too large? We cannot just continue receiving
data forever. Is there a "permissible" way within SMTP to abort
during data, or should I just ignore these ambiguous requirements,
and either: 1) Send a TCP reset, or 2) Let the transmitter hang.
Arnt mentioned the RFC for for SMTP Service Extension for message
size declaration. You can send a TCP reset to abort the
connection. The SMTP client will retry delivery. If you want to say
"payload too large", you'll need to send a 552 code before you get to
the DATA phase.
Section 18.104.22.168.7 of RFC 5321 discusses about the maximum total
length of a message content. There isn't a permissible way within
SMTP to abort during DATA. It's a "don't do it unless you know what
you are doing".