Resolve ‘Sender IP Blacklisted’ Email Error | Troubleshooting Guide
Resolve 'Sender IP Blacklisted' Email Error
Learn how to address email sending and receiving issues related to greylisted IPs.
Error: 'Sender IP Blacklisted'
This error occurs when the sender’s IP address is greylisted, preventing emails from reaching your inbox or blocking your sent emails.
Case 1: Not Receiving Emails
If you’re not receiving emails from specific contacts, the sender might receive a bounce notice due to greylisted IP addresses. This can happen because our mail server utilizes Realtime Blackhole Lists (RBL) to filter spam.
Explanation: The sender's IP is checked against DNS-based greylist services (known as RBLs or DNSBLs). If found on these lists, the email is rejected and will not be delivered.
Example Error: 550 Sender IP (XX.XX.XX.XX) is greylisted at new.spam.dnsbl.sorbs.net
Unfortunately, IPs cannot be whitelisted directly. To allow emails from these senders, you can disable blacklist protection for specific mailboxes via the Email Accounts section in your hosting control panel.
Case 2: Not Sending Emails
When using our SMTP server without authentication, your ISP’s IP may be greylisted, blocking outgoing emails. You might see the following error:
Example Error: 550 Sender IP (XX.XX.XX.XX) is greylisted at new.spam.dnsbl.sorbs.net
Solution: Enable SMTP authentication in your email client settings:
- Outlook: Check "My server requires authentication"
- Eudora: Enable "Authentication allowed"
- Mozilla: Select "Use name and password"
- Mail for Mac OS X: Check "Use authentication when sending"
Tags: DNSBL, Email bounce, email error, email not received, greylisted IP, mail server issues, RBL, Sender IP blacklisted, SMTP error