Recently, my zimbra mail cannot sent the mail outside th lochost and receive following error messages:
Service unavailable; Client host [mail2.abc.com.hk] blocked using
blackhole.securitysage.com; This list is offline. Please stop querying for
it. (in reply to RCPT TO command)
I guess the blackhole.securitysage.com is out of service, but I did not know how to delete the block list in the zimbra server.