A permanent rejection for policy reasons, similar to 550 5.7.1: spam filtering, blocklists, relay denied or a recipient rule.
Policy rejection · fixable
Common causes
- Spam or phishing filter matched the message
- Your IP or domain is blocklisted
- Relay access denied (sending through someone else's server without logging in)
How to fix it
- Read the text after the code and paste it into the Bounce Explainer
- Check blacklists and authentication
- If relay denied: enable SMTP authentication in your mail client
Blacklist CheckerRun the right check for your domain or paste the full bounce message for a precise explanation.
Open Blacklist Checker →Frequently asked questions
What is the difference between 550 and 554?
550 usually concerns a specific recipient or action; 554 means the whole transaction failed. Both are permanent.