A catch-all permanent failure code used when the server cannot categorize the specific error. Check the accompanying SMTP reply code and message text for more details about the actual failure reason.
What Does Error 5.0.0 Mean?
Enhanced status code 5.0.0 is a generic permanent failure indicator used when the receiving server cannot provide a more specific enhanced status code. It is often paired with SMTP reply code 550 or 554 and serves as a fallback when the server's error classification system does not have a specific code for the situation.
Because 5.0.0 is generic, the real information is in the SMTP reply code and the human-readable text that accompanies it. Always read the full bounce message to understand what actually happened. Some older mail servers that do not support detailed enhanced status codes will use 5.0.0 for all permanent failures.
Common Causes
- Server does not support detailed enhanced status codes
- Error condition does not match any specific enhanced code
- Legacy mail server with limited error reporting
- Multiple simultaneous issues preventing delivery
How to Fix Error 5.0.0
- Read the full bounce message text for the actual error description
- Check the accompanying SMTP reply code (550, 554, etc.) for classification
- Verify recipient address, authentication, and sender reputation as general troubleshooting
Frequently Asked Questions
Bounce code 5.0.0 means "Other undefined status" -- a permanent delivery failure where only the general error class is known, but the specific cause is not defined. It is a catch-all error code used when the mail server cannot provide a more specific reason for the rejection. The "5" indicates a permanent failure, meaning the email cannot be delivered in its current form without changes.
Start by verifying the recipient's email address for typos, missing letters, or incorrect domain names. If the address appears correct, contact the recipient through another method to confirm it is still active. Check your sending domain's DNS records (SPF, DKIM, DMARC) for proper configuration. Since 5.0.0 is a generic code, the accompanying bounce message text often contains additional details about the actual cause -- read the full bounce notification carefully.
The 5.0.0 code is a hard bounce, indicated by the leading "5" which signifies a permanent failure. Hard bounces mean the email cannot be delivered and will not succeed on retry. However, note that 5.0.0 is often an interpretation provided by your email service provider rather than the raw SMTP response from the recipient's server. Remove addresses that consistently return 5.0.0 bounces from your mailing list to protect your sender reputation.