I have an issue which is driving me nuts. I've already contacted the administrator of this server and it insists the error is in my zimbra server, and not on his qmail server (which I insist).
When sending emails to this server, the mail bounces to me with this error on the email body.
PS: I have no currently other issues when sending/receiving email to/from other servers, so my suspection on this issue as being a problem on his server. Also, how arguments can I use to convince him?451 qq temporary problem (#4.3.0)