Zimbra Relay Access Denied -
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In this post, we’ll break down why this happens and the three most common ways to fix it. An SMTP relay is when a mail server accepts a message and delivers it to a domain that is not its own.
Add the external domain to the list of allowed "From" addresses: zimbra relay access denied
zmprov modifyAccount [email protected] +zimbraAllowFromAddress [email protected] zmprov fc account [email protected] This is a classic "broken copier" or "buggy CRM" problem. Printers, scanners, and legacy applications often hard-code an IP address and try to send mail without logging in.
If you manage a Zimbra Collaboration Suite (ZCS) environment, you’ve likely seen the dreaded "554 5.7.1 <[email protected]>: Relay access denied" error in your mail logs. Found this helpful
By default, Zimbra’s Postfix (the MTA underneath) is configured as a closed relay. This prevents spammers from abusing your server to send thousands of emails to Gmail or Yahoo. When you see "Relay Access Denied," Zimbra is saying: "I don’t know this sender, and I’m not responsible for the destination domain—so I’m refusing this message."
zmprov getServer `zmhostname` | grep zimbraMtaAuthEnabled It should return TRUE . If you’ve configured a “Send As” alias (e.g., sending as @gmail.com from your Zimbra webmail), Zimbra will reject it unless you’ve explicitly allowed it. An SMTP relay is when a mail server
| Setting | Command to Check | Desired State | | :--- | :--- | :--- | | | zmprov getServer zimbraMtaTlsAuthOnly | TRUE | | Submission Port | zmprov getServer zimbraMtaAuthEnabled | TRUE on port 587 | | Trusted Networks | zmprov getServer zimbraMtaMyNetworks | Only internal subnets | Final Thoughts "Relay access denied" is frustrating because it stops legitimate email. But remember: without this guardrail, your Zimbra server would be an open relay—and it would be blacklisted within hours.
Add the device’s IP address to Zimbra’s “mynetworks” setting. This tells Zimbra, "Trust anything coming from this IP."
