Mark Delany wrote:
Do you mean the server's side of the connection will have buffer
data in it? That would mean the client sent DATA<CR><LF> followed
by header/body information, possibly even in the same packet,
without waiting for the reply from DATA. The server could drop the
connection
I haven't been watching lately, but at some point a popular bot
technique was to send the whole transaction without looking at the
responses. After all, what do they care?
It was popular enough to generate the "greet_pause" feature in
sendmail - as you must know. I don't know whether "greet_pause"-type
detection is so wide-spread now that spammers have moved away from
doing it, but I'll bet a lot still don't care and just blast away.
Yup. Bad clients attempting to behave as a RFC 1854 PIPELINING client
still occurs out there regardless if the SMTP server doesn't even
advertise Pipelining EHLO response support. They are blasting away at
random sites to see what sticks to get their foot the door which is
basically step one - message acception. They really don't care if you
reject/discard before or afterwards. Furthermore, I venture that most
mom and pop spammers, doesn't invest too much money in getting SMTP
clients compliant with SMTP.
In any case, non-PIPELINING servers should count consecutive bad
command errors and drop the session. Pauses just delays the session
completion and can affect incoming worker queue designs.
==
HLS
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