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I've moved an older Sendmail/Dovecot system to a Zimbra community edition system. I need to be able to receive messages from certain standalone Linux hosts that may not have valid A records or proper reverse DNS entries established (e.g. AT&T is the ISP or systems sitting on a consumer-level ISP). Establishing the reverse DNS or setting a SMARTHOST is not an option.

The error I get in zimbra.log is:

zimbra postfix/smtp[2200]: DB83B231B53: to=<>, relay=none, delay=0.07, delays=0.06/0/0/0, dsn=5.4.4, status=bounced (Host or domain name not found. Name service error for type=A: Host not found

How can I override this? Is this more of a Postfix issue or is it Zimbra?

edit - The problem seems to be with an underscore in the hostname of the server. So it's a problem with Again, how can I override this in Zimbra?

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up vote 1 down vote accepted

I believe this is a postfix error. Have a look in the Zimbra Admin under Global Settings MTA and double check the protocol and DNS check settings that you're using. You may have to relax the fully qualified domain name requirement or disable DNS lookups.

I've never had to solve this problem so I can't be sure that this is what's causing your problem. But that's where I'd start.

EDIT: Just had another thought. Verify that your Zimbra server has functional DNS. It's possible the name resolution isn't working which could manifest itself in this manner.

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Question has been updated with additional info... – ewwhite May 23 '11 at 20:12

clear Client's IP address (reject_unknown_client) in zimbra global settings

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