We've been using Zimbra for 3 years now and it is only this month that we have an issue with the domain disco.co.jp. Our Zimbra server was not using a split DNS setup and has its own live IP address.
All emails send to this domain was deferred with an error "conversation with ns1.disco.co.jp[18.104.22.168] while sending end of data -- message maybe sent more than once."
This has happened 3 days. We have change the IP address of our mail server thinking it was blocked though our previous IP was not listed in any RBL sites.
They are telling us to relay our email to them to ns3.disco.co.jp which is not included in their MX server. This is an excerpt of what he told us (JJLee is a Korean that know how to speak Japanese but not quite good in English)
"Good afternoo. Mr.Panagan, This is JJLee. Tomorrow, If you have a time could you try to change a 3rd server of DISCO domain. SMTP 3'rd Server Disco Domain
And resetting DB with Postmap transport postfix transport file disco.co.jp relay:ns3.disco.co.jp"
How do you translate this? Maybe this email is not intended for us.
Thanks for the help. I would send log files if needed.