On 2021-11-29 6:57 a.m., Larry M. Smith via mailop wrote:
On 11/24/2021, Michael Peddemors via mailop wrote:
CONN: 40.107.96.87 -> 25 GeoIP = [US] PTR =
mail-sn1anam02on2087.outbound.protection.outlook.com OS = Windows NT
kernel
Returning 250 ok [qp 3539411] for data
QUIT command received, args:
And then it terminates the connection, SSL collapses, without waiting
for the remote mail server to acknowledge the QUIT.
I get it that they 'might' think that closing when 'they are done' and
we gave a 250ok on the DATA, and they sent the QUIT.. I don't know,
thinking to shave a few milliseconds off of the connection, but the
RFC is pretty clear that a QUIT .. AND .. and acknowlegement is part
of RFC.
Comments? (And no, there is zero lag before they terminate)
If I understand you correctly;
When sending mail, *.outbound.protection.outlook.com appears to send
DATA, terminate via <CRLF>.<CRLF>, wait for a response, then issue QUIT
immediately followed by a TCP FIN packet.
Operationally, I don't think it makes a difference. RFC pedantics?
Maybe. Does the receiving system advertise the Pipelining SMTP Service
Extension?.. Does setting/un-setting that response to EHLO make a
difference to outlook.com's behavior? If so, does and/or should RFC2920
allow for QUIT->TCP FIN?
No, Pipeline is not advertised, the RFC's say that when you send a
command, if you are NOT using pipelining, you need to wait for a
response, and that includes the QUIT.. wait for the receiving system to
send an OK in this respect, not only does it satisfy RFC's but also
helps differentiate from the many spamming systems that terminate as
quickly as they can to reduce overhead when spamming.
--
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