Outbound Connection to External Mail Gateway Randomly Not Using Authentication
Last updated on DECEMBER 28, 2017
Applies to:Oracle Communications Messaging Server - Version 7.0.1 to 8.0.0 [Release 7.0.0 to 8.0.0]
Information in this document applies to any platform.
A tcp_* channel has been configured to use SMTP authentication for outbound connections to a certain remote MTA. (See the AUTH_PASSWORD and AUTH_USERNAME and EXTERNAL_IDENTITY options.)
Occasionally some mail in that channel queue will fail with an "R" status code in mail.log_current. The error from the remote MTA is simply "550 #5.1.0 Address rejected."
Investigation on the remote MTA revealed that these failures were because SMTP authentication was not being used.
So it seems that randomly SMTP AUTH is not used. It works most of the time, but occasionally it tries to send a message without first authenticating.
Enabling master_debug on the channel revealed that the failures only to messages after the process has already sent 10 messages to that remote MTA on that connection. It starts a connection, does SMTP Authentication as it is configured to do, sends the first 10 messages, disconnects, connects again, and tries to send another message without first doing SMTP Authentication.
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