5.7.0

Enhanced Status Code 5.7.0: Other Security or Policy Status

Permanent failure Critical severity Security RFC 3463
What it means

Enhanced Status Code 5.7.0 means “Other Security or Policy Status.” A permanent rejection on security or policy grounds where the receiver has not narrowed the reason further. Gmail uses it for at least ten distinct refusals, so the text after the code is the whole diagnosis.

At a glance
Code5.7.0
Bounce typeHard (permanent)
SeverityCritical
CategorySecurity
What to doSuppress the address; do not retry
StandardRFC 3463
What it looks like in your mail logs 
550 5.7.0 Mail relay denied. Invalid credentials, or the sending domain is not registered with this service

What does 5.7.0 mean?

Enhanced status code 5.7.0 is the catch-all for the security and policy class. RFC 3463 defines X.7.0 as other or undefined security status, meaning something security-related caused the message to be returned but the receiver is not committing to a more specific sub-code.

Google leans on it heavily and in very different situations: relay denied because credentials are invalid or the domain is unregistered, an account suspended for abuse, sending denied outright, too many unauthenticated commands, authentication required, STARTTLS required before proceeding, no identity changes permitted, and content that presents a security issue. Those have almost nothing in common except the class. A 550 5.7.0 about relay denial and a 552 5.7.0 about message content are different problems with different fixes sharing one number.

That makes 5.7.0 the clearest case on the whole site for reading the text rather than the code. The reply code helps narrow it: a 530 5.7.0 is an authentication demand, a 552 5.7.0 concerns the message itself, and a 550 5.7.0 is usually relay or account related. Beyond that, the words the server chose are the only diagnosis available.

How 5.7.0 plays out

Your server attempts delivery
The recipient server returns a permanent 5.7.0 rejection
This is a hard bounce: the message will not be accepted as sent
Suppress the address and fix the root cause before resending

Where 5.7.0 sits: soft vs hard bounce

Soft bounce (4xx) Hard bounce (5xx)
NatureTemporaryPermanent
SMTP class4xx5xx
What to doLet it retrySuppress the address
Recoverable?OftenNo
5.7.0 is✓ this code

What each provider means by 5.7.0

A registered code does not oblige a provider to use it that way, and the large ones diverge. Match the wording in your own bounce, not the definition above.

Gmail Used for relay denial, suspended accounts, authentication demands, STARTTLS demands and content security Reference

Common causes of 5.7.0

  • Relay was denied because credentials are invalid or the domain is not registered with the service
  • The sending account has been suspended for abuse
  • Authentication is required and was not supplied, or STARTTLS was required first
  • The message content was judged to present a security issue
  • Too many unauthenticated commands were issued in one session
  • The server refuses identity changes, such as a MAIL FROM that does not match the authenticated user

How to fix 5.7.0

  • Read the text after the code, because the sub-reason is the only real diagnosis here
  • Use the reply code as a narrowing hint: 530 means authenticate, 552 concerns the message, 550 usually relay or account
  • If relay was denied, confirm the sending domain is registered with the relay and the credentials are current
  • If authentication is demanded, enable SMTP AUTH over TLS and stop sending unauthenticated
  • If the account is suspended, resolve the abuse report rather than retrying
  • If content was flagged, audit links, attachments and any redirect service in the message

Frequently asked questions

What does SMTP error 5.7.0 mean?
It means a permanent refusal on security or policy grounds where the server has not given a more specific code. It is deliberately broad: RFC 3463 defines it as other or undefined security status. Because Gmail alone uses it for around ten distinct refusals, the code by itself tells you almost nothing and the accompanying text tells you everything.
How do I narrow down a 5.7.0?
Start with the reply code in front of it. 530 5.7.0 is a demand to authenticate or to start TLS. 552 5.7.0 concerns the message itself, usually content judged to be a security risk. 550 5.7.0 is most often relay denial or a suspended account. Then read the sentence the server returned, which is where the actual reason lives.
What does "relay denied" mean in a 5.7.0?
It means the server will not accept mail from you for that destination, because it does not recognise you as an authorised sender. Either the credentials supplied are wrong or expired, or the sending domain has not been registered with the relay service. It is a configuration and authorisation problem, not a reputation one.
Is 5.7.0 the same as 5.7.1?
They are neighbours with different levels of commitment. 5.7.1 says delivery was not authorized and the message was refused, which points at policy or filtering against you specifically. 5.7.0 declines to say which security reason applies. In practice receivers use them somewhat interchangeably, so treat the text as authoritative over the choice between the two.
Should my server retry after 5.7.0?
No. The leading 5 makes it permanent and retrying will not change the outcome. Worse, repeatedly retrying against a provider that has issued a permanent refusal is itself a negative reputation signal. Suppress, diagnose from the text, and only resume once the underlying cause is fixed.

Related bounce codes

5.7.1 Delivery Not Authorized - Message Refused 5.7.4 Security Features Not Supported 530 Authentication Required 5.7.8 Authentication Credentials Invalid 4.7.0 Other Security or Policy Status - Temporary 5.0.0 Other Undefined Status

Sources & further reading

RFC 3463 · The standard that defines this reply code IANA registry · The authoritative list of enhanced status codes and their meanings Gmail SMTP errors and codes · Google Workspace reference for every code Gmail returns
Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026 ← All bounce codes