550 “Administrative Prohibition” or "Relay Access Denied"

The 550 “administrative prohibition” or “relay access denied” bounce error is generated when a recipient mail server detects that our service hasn’t been given consent to send email on behalf of the sending domain, which is deemed suspicious and subsequently blocked.

This error can be resolved by adding your domain to the Verified Senders list. If the error message persists with a verified sending domain, have the recipient whitelist our sending IP addresses with their incoming mail server.

If that fails, make sure your FROM address is the same as any domains listed in your Verified Senders.

Note: High volume accounts may have their recipients whitelist their dedicated IP address(es) instead of our entire range of sending IPs. Check the “Settings > Dedicated IPs” section of the account’s dashboard to identify the correct address(es) to whitelist.

If you have questions regarding our USA-based SMTP services or any other part of SMTP2GO then please contact our support team who are happy to assist further.