I have a hosted Zimbra with multiple domains all sharing one IP address. I notice that my log contains varies error messages. Some of them includes:
- Relaying denied. IP name possibly forged [xxx.xxx.xxx.xxx] (in reply to RCPT TO command))
- Host or domain name not found. Name service error for name=zimbra.xxx.com type=A: Host found but no data record of requested type
- mail for zimbra.xxx.com loops back to myself
After some research, I realize that beside getting Zimbra to run properly, we have to setup additional verification stuffs to ensure that Zimbra is able to send/receive email without rejections to/by other servers:
* Have a valid rDNS
* Have SPF set up
* Have domain keys set up
* Have signed up for feedback loop
* Have a valid abuse@ and/or postmaster@ email address on your domain
Since many users complains that they cannot receive/send emails to/from some domains, should I also disable these checks in Zimbra MTA settings?
- Hostname in greeting violates RFC (reject_invalid_hostname)
- Client must greet with a fully qualified hostname (reject_non_fqdn_hostname)
- Sender address must be fully qualified (reject_non_fqdn_sender)
- Client's IP address (reject_unknown_client)
- Hostname in greeting (reject_unknown_hostname)
- Sender's domain (reject_unknown_sender_domain)
Zimbra has provide a good reference manual on what it's each option does. Unfortunately it didn't provide something more useful - an operation manual (step by step installation and setup guidance)