MailFixIt

Generic SMTP delivery response

Understand SMTP 5.7.0: Generic security or policy rejection

A security policy permanently rejected this attempt, but the enhanced code alone does not reveal which rule matched.

Problem description

A representative response is:

550 5.7.0 Generic security or policy rejection.
Is this temporary or permanent?

Do not repeatedly resend the same message. Correct the cause named in the full response first.

What this response means

Standard 5.7.0 Other or undefined security status says only that a security or policy issue caused a permanent failure. Receivers can use it for unrelated authentication, relay, access, content, or abuse decisions.

What to do

  1. Preserve the complete response, receiver hostname, timestamp, sender, recipient, connecting IP, and message ID.
  2. Match the exact text to the correct owner: account administrator, sending host, recipient policy, content generator, or provider reputation team.
  3. Correct SPF, DKIM, DMARC, or PTR only when the response actually names that failure.
  4. Stop and investigate compromised accounts or unusual outbound traffic before retrying.
  5. Generate one controlled test after the named problem is fixed.

Changing several DNS records at once destroys evidence and can introduce new failures.

What MailFixIt can check

MailFixIt can inspect public authentication records when they are relevant. It cannot reproduce private content filters, account permissions, or a historical reputation decision.

Prefer a provider-specific page that matches the complete bounce wording.

Frequently asked questions

What does SMTP 5.7.0: Generic security or policy rejection mean?

A security or policy condition caused a permanent rejection, but the generic code intentionally does not identify the exact rule.

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 550 5.7.26: Multiple authentication checks failedUnderstand SMTP 5.7.26 and separate SPF, DKIM, DMARC, and alignment failures before changing email DNS.

Primary sources: IANA SMTP Enhanced Status Codes.