I am facing interim issue with my oracle DB. where smtp relay is working for 99% of emails sent but only 1% being sending failed with error "SMTP transient error:421 Service not available". I am unable to trace any log entry for missed emails at exchange end in smtp receive logs.
please guide how to trace and resolve the issue. both my server are available not network connectivity issue. ping telnet trace won't show any outage or disconnect.
Br,
AA