550 Administrative Prohibition

The “550 Administrative Prohibition” error usually means that the receiving mail server is rejecting the message due to a policy restriction. Given that you are using SmarterMail with a SpamExperts gateway, here are some potential causes and solutions:

Possible Causes & Solutions:

1. SpamExperts Filtering Issue
   • If your outgoing mail is being routed through SpamExperts, it might be rejecting the message due to spam filtering rules.
   • Solution:
     • Check the SpamExperts log for outgoing messages.
     • Look for SMTP rejection logs under “Outgoing” or “Email Delivery Logs” in SpamExperts.
     • Whitelist your own domain or IP if necessary.
2. SmarterMail Gateway Settings
   • Your SmarterMail SMTP Gateway might not be correctly configured.
   • Solution:
     • Go to SmarterMail Admin Panel → Settings → Gateways / Load Balancing and check the outbound gateway settings.
     • Ensure that the SpamExperts SMTP hostname, port, and authentication details are correct.
3. Blacklist / RBL Issue
   • The IP you are sending from could be blacklisted.
   • Solution:
     • Check your sending IP at MXToolbox Blacklist Check.
     • If blacklisted, request delisting or use another outgoing IP.
4. Incorrect SPF, DKIM, or DMARC Settings
   • Some receiving mail servers block messages if your domain authentication records are incorrect.
   • Solution:
     • Verify SPF, DKIM, and DMARC using a tool like https://www.mail-tester.com/.
     • Ensure SPF includes the SpamExperts gateway: v=spf1 include:_spf.spamexperts.com ~all
5. SMTP Restrictions by the Receiving Server
   • Some mail providers block emails if they detect suspicious content or attachments.
   • Solution:
     • Try sending a plain text email to test.
     • Remove any large attachments or suspicious links.
6. Check if You Are Using an Open Relay
   • If your SmarterMail server is misconfigured as an open relay, SpamExperts may be rejecting your emails.
   • Solution:
     • Ensure SMTP Authentication is enabled in SmarterMail.
     • Under Security → Anti-Spam, check relay settings.

Next Steps

1. Check SpamExperts logs to see why the email is rejected.
2. Verify SMTP gateway configuration in SmarterMail.
3. Test email deliverability using tools like MXToolbox or Mail-Tester.
4. If needed, contact SpamExperts support with log details.

Would you like guidance on checking specific logs in SpamExperts or SmarterMail? 🚀