Message: error while proxying request to target server: Connection refused Error code: service.PROXY_ERROR Method: [unknown] Details:soap:Receiver
Error found with the proxy in log file: /opt/zimbra/log/mailbox.log
The mbox was trying to access a new mbox that wasn’t setup properly.
found another error in mailbox.log.
zimbraloghostname server = null
zmprov gacf | grep zimbraLogHostname
and it showed that it was pointing to the new broken mbox
finally had to change the good mailbox servers config
zmprov mcf zimbraLogHostname
zmprov mcf zimbraLogHostname my.mymail.com