On 10/4/2018 2:21 PM, Ryan Krueger wrote:
Mark,
We completed a packet capture to a server that is not behind a load balancer. A message was delayed 15 minutes with the same error message shown in the EOP UI: "450 4.4.316 Connection refused [Message=Socket error code 10061]”. However, there were no connection attempts from Microsoft during that time. There is no RST sent from our hardware to Microsoft. This does seem to narrow the search.
I'm not sure I'm interpreting the whole problem correctly but isn't the 450 code supposed to be a 3-digit response code that was sent by the receiving system to the sending system? If the sending system never established a connection because its connection attempt was refused, isn't it misleading for the sending system to report a 450 as part of the error?
Per RFC 5321
SMTP clients that experience a connection close, reset, or other communications failure due to circumstances not under their control (in violation of the intent of this specification but sometimes unavoidable) SHOULD, to maintain the robustness of the mail system, treat the mail transaction as if a 451 response had been received and act accordingly.
I can understand treating the behavior of the transaction as if a 450 occurred but it seems like a bad idea to literally have a 3-digit 450 as part of the error. Fine to have "4.4.316 Connection refused [Message=Socket error code 10061]" but to me starting off with a 450 or any other 3-digit code makes it look like the sending system received a response code when it couldn't have if all it got was a RST.
- John J. _______________________________________________ mailop mailing list [email protected] https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
