Gmail delivery response

Gmail 550 5.7.0: Email relay denied or email sending denied

Google uses 550 5.7.0 for several SMTP relay rejections. The complete sentence identifies whether the sender IP or domain is unregistered, credentials are invalid, an account is suspended for abuse, or sending is denied.

Problem description

A representative response is:

550 5.7.0 Email relay denied 192.0.2.10. Invalid credentials for relay for one of the domains in: example.com.

Is this temporary or permanent?

Treat this as permanent until the complete provider response and retry behavior show otherwise.

Match the response to the fix

domain or IP ... isn't registered: add the intended sender IP in Google Workspace SMTP relay settings, or use an authorized route.
Invalid credentials for relay: correct SMTP authentication and use an account in the intended Workspace domain.
account ... suspended due to abuse: stop the traffic, secure the account, and follow Google’s recovery process.
Email sending denied: review the account and relay configuration named in the response.

How to resolve it

Save the complete response, sending IP, account, and timestamp.
Open the Workspace SMTP relay settings for the account that owns the route.
Correct only the IP, domain, authentication, or account condition named by Google.
Send one controlled test through the same route.

MailFixIt scope

This is mainly a Google Workspace relay or account setting, not a public DNS diagnosis. MailFixIt cannot modify relay permissions or restore a suspended account.

Frequently asked questions

What does Gmail 550 5.7.0 mean?

Google rejected SMTP relay or sending. The remaining response text states the specific account, credential, IP, domain, or abuse condition.

Can MailFixIt prove this entire bounce from public DNS?

No. The current checker can evaluate selected public DNS configuration, but it cannot recreate recipient state, credentials, reputation, message content, or a historical provider SMTP decision.

Related email diagnostics

SMTP 5.7.1: Delivery not authorizedSMTP 5.7.1 means delivery is not authorized; use the full response to identify a recipient restriction, relay permission, transport rule, or filtering policy. Gmail 550 5.7.1: Delivery not authorizedGmail 550 5.7.1 is a broad permanent rejection; match the exact response text to a policy, relay, reputation, header, rate-limit, or IPv6 problem before acting.

Primary sources: Gmail SMTP errors and codes, Google email sender guidelines.