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SMTP Bounce Code 5.3.2: System Not Accepting (Permanent)

SMTP bounce code 5.3.2 indicates that the receiving mail server is permanently not accepting network messages. This is a permanent failure (hard bounce), meaning the mail server has a persistent issue preventing it from accepting emails.

What Does 5.3.2 Mean?

The enhanced status code 5.3.2 follows the SMTP Enhanced Status Code format:

  • 5 = Permanent failure (hard bounce)
  • 3 = Mail system status (related to the mail server infrastructure)
  • 2 = System not accepting network messages

When you receive a 5.3.2 bounce, it means the receiving mail server has a permanent configuration or operational issue that prevents it from accepting incoming messages. This is different from 4.3.2 (temporary) in that the problem is persistent.

Bounce Type

  • Type: Hard bounce (permanent failure)
  • Category: Technical
  • Action Required: Remove the email address from your mailing list or contact the recipient

Common Causes

  1. Permanent Server Shutdown: The mail server has been permanently shut down or decommissioned
  2. System Misconfiguration: The mail server has a permanent misconfiguration that prevents message acceptance
  3. Service Disabled: Mail services have been permanently disabled on the server
  4. Network Configuration Issues: Permanent network configuration problems preventing message acceptance
  5. Firewall Blocking: Permanent firewall rules blocking incoming connections
  6. Abandoned Infrastructure: The mail server infrastructure is abandoned or no longer maintained
  7. Policy Rejection: Permanent policy that prevents the system from accepting messages
  8. System Migration: The mail system has been migrated and the old server no longer accepts mail
  9. Decommissioned Server: The server is being decommissioned and is no longer accepting new connections
  10. Critical System Failure: Critical system failure that has permanently disabled mail acceptance

How to Resolve

For Email Marketers

  1. Remove from List: Immediately remove the email address from your active mailing list
  2. Contact Recipient: If possible, contact the recipient through alternative channels to verify their mail server status
  3. Document the Issue: Document which domains are affected by permanent system rejection
  4. Monitor for Recovery: Periodically check if the issue has been resolved (though unlikely)
  5. Use Alternative Channels: For important communications, use alternative contact methods

For Developers

  1. Remove from Database: Immediately remove the email address from your sending database
  2. Implement Bounce Handling: Set up automated bounce processing to remove 5.3.2 bounces from your database
  3. Log System Patterns: Track which mail servers have permanent acceptance issues
  4. Suppression List: Add these addresses to a suppression list to prevent future send attempts
  5. Monitor Domain Status: Periodically check if domains with 5.3.2 errors have resolved their issues

Investigation Steps

When you receive 5.3.2 bounces, investigate:

  1. Check Domain Status: Verify if the domain and mail server are still active
  2. Test Server Availability: Try connecting to the mail server to verify its status
  3. Check MX Records: Verify if MX records are still valid and pointing to active servers
  4. Contact Support: Contact the recipient's IT department if possible
  5. Document Pattern: Document if multiple addresses from the same domain are affected

Related Bounce Codes

Examples

Example Bounce Message

550 5.3.2 System not accepting network messages
The mail server is permanently not accepting incoming messages.

Example Enhanced Status Code

550 5.3.2 <[email protected]>: System not accepting network messages - service disabled

Common Email Provider Responses

  • Generic: "550 5.3.2 System not accepting network messages"
  • Service Disabled: "Mail service permanently disabled"
  • System Error: "System permanently unavailable"
  • Enterprise: "Mail server permanently not accepting connections"

Best Practices

  1. Never Retry: Don't attempt to resend emails to addresses that bounce with 5.3.2—they will continue to fail
  2. Remove Immediately: Remove addresses with 5.3.2 bounces from your mailing list immediately
  3. Use Suppression Lists: Maintain suppression lists to prevent sending to permanently unavailable systems
  4. Monitor Domain Health: Track domains with permanent mail system issues
  5. Contact Recipients: If possible, contact recipients through alternative channels
  6. Document Issues: Keep records of domains with permanent acceptance issues
  7. Check MX Records: Verify MX records for affected domains to understand server status
  8. Review Periodically: Periodically check if issues have been resolved (though unlikely for permanent failures)